No, its a not a flawed argument. From both a reality and a professional risk management perspective.
Technically speaking always jumping to "avoidance" as a risk management strategy is absurd and illogical. Transference, probability reduction, impact reduction, contingency planning, and acceptance are all perfectly rationale counters that bear examination.
Common sense tells us what things are good to avoid and what isn't.
If "avoidance" was "absurd and illogical" then our roads would be total chaos.
Common sense tells us we can't make a 90° corner at 100mph so we avoid doing it.
Common sense tells us we shouldn't drive at 100mph in heavy snow.
If everyone set out today to with idea of ditching common sense and NOT avoiding what they perceive as risks it would be like a war zone out there by lunch time.
Don't get me wrong, as a species we have evolved in a major part by those who push the boundaries of these risks.
We all take risks on a daily basis, be it driving that little bit faster because we're late, having yet another fry up this week, not wearing a helmet today on the way to work, etc etc
Most of us will be fine, but there will still be many people that will die today simply because they ignored common sense.
That might be as a result of a RTA, heart disease, obesity, smoking, drug overdose, working with heavy machinery etc etc etc
All those people weighed up the risk and made a decision that proved to be wrong much to their detriment.
Yes there is a chance that someone might knock a candle over. There is also the chance that someone might be struck by lightning - so perhaps they shouldn't go outdoors in the first place.
You are using a fundamentally flawed argument again.
The chances of being struck by lightening is extremely low, but would you walk around on the top of a mountain in the middle of a thunder and lightening storm though?
My guess is no.
But using your initial hypothesis of "nothing happened to me" it should be fine to do as i've camped on the top of a mountain through a thunder storm and i didn't die.
The OP enquired about tealights and did not plan to so lets not examine the risks for a different scenario.
Sorry for being pedantic here mate, but it was you that bought up the comparison to a gas lantern
My brother and I used to camp on Dartmoor a third of a century and more ago and used a gas lantern in small backpacker tents.
You also bought up the scenario of being hit by lightening.
Hands up, i'm also guilty of using several different scenarios though
I do think it's a good comparison method to use an analogy as long as we stay within the realms of being sensible.
My point is this, if our purpose is to reduce all risk to zero, we would never go out in the first place. We might slip on a wet rock - so only go out in the dry. We might cut ourselves - so lets not use a sharp knife. We might cut our foot - so lets not use an axe. All of these have happened to members of the forum - they are real risks that we choose to accept. We may choose to reduce their probability by using things with care. We may choose to reduce the impact of an accident by having a first aid kit. But we choose to take the risk. Some of us may prefer candle light to electric light. So, following the same rationale, we might choose to ensure ventilation and to use a candle lantern to lessen risk. We might even use a cotton tent. But we may choose to take the risk - as we should as adults.
You are using extremes to the point of absurdity to forward your point again though mate.
No one is saying don't use a axe, knife etc.
If you need to cut something you need a sharp tool, the risks associated with cutting something with a blunt tool are oddly higher.
Likewise a tool like an axe is the most sensible and logical tool for cutting down some tress.
In these instances there is a goal that can't be served by using an alternative.
In this case though a modern torch is gives off an adjustable output of light, will be cheaper over time, be lighter on multi night trips AND safer.
So as a illumination source there are far far better alternatives to use inside a tent.
As a heat source, in a well ventilated tent to heat would not be perceivable, you might get your hands a bit warmer if you hold them over it, but as as heat source for your core it's a fundamentally flawed idea.
You'd either need a LOT smaller space, or a larger candle.
So as a source of heat a sleeping bag or warmer clothing is a better option.
The one thing this hobby really doesn't need is a self appointed arbiter of what is the "right choice to make"
Again you are going to the extreme mate.
Who is acting as a "self appointed arbiter"
No one is saying DO NOT DO IT or YOU WILL DIE if you do.
I can't see anyone blowing the risks out of proportion.
People are pointing out things to be cautious about like small tents etc, they are then giving their own personal opinion of what they would do.
Personally i'm just asking why would you use a candle in tent.
As a reminder the op asked
Can you have a burning tealight in a tent without worrying about CO and setting light to your tent if placed in a glass jar ?
As i can only give my opinion, personally i wouldn't be without worry