If that's all it takes for you to be incredibly offended, then a sport where people shoot projectiles at you in simulated combat might not be a good fit for you.
Trust me, if someone asked me kindly if I would please show my ID, I defenitely would. If someone told me in a harsh tone "no kids allowed" I would be pretty pissed. As would most people that are legal adults. And I don't exactly see how being offended at someone for being rude to a potential customer for how they look would possibly impair my ability to play airsoft.