Given the choice between cotton and man-made, why buy the item that you know will not perform well in a fire, whether in a plane or a car?
I'm being beaten-up on another forum regarding safety at the moment so I might as well go the whole hog....
I guess there is a "pure" form of safety awareness which we all deal with in our day to day lives in the home etc There is then "applied" safety: don't smoke in petrol stations, wear a seat belt and so on. Then there is "application" safety:such as if you are a climber, parachutist, racing driver etc, all dangerous sports which have safety equipment that lowers some of the risk.
Private flying is difficult. In spam cans, we don't tend to wear helmets,nor do we tend to wear Nomex flying suits. To be honest, I check the fire extinguisher and have some sort of plan about what I'd do if I had a fire in the air and had to get down quickly but I probably try not to think too hard about it. The reality is that if you've got a bit of smoke at 2000ft you have a chance. If flames are licking around your hands and feet or you've gone in hard from a stall well......cloud, new harp and "Nearer my God to Thee" springs to mind.
It's a risk game and we all conciously or otherwise take it because, despite the horror stories, that odds are stacked well in our favour even though we are putting wings on a 128litre avgas tank and taking it flying. So, I don't think I'll be buying my shirts on the basis of being in a fire.
However, in private flying, it's a matter of choice.....but will you require your passengers to wear them as well?