I guess I see it more as vapers saying they won't stand for promoting underage use, which would be breaking the law. We may get it wrong in some instances but the general message is getting sent out there. I personally am not against underage persons vaping but get very uncomfortable when we're talking about very young kids, which I at first thought this girl was.
I don't necessarily see being against age restrictions as promoting underage use. I wouldn't encourage teens to vape, just as I wouldn't encourage them to drink energy drinks, or eat fast food every day. The two ideas are not mutually exclusive.
As for very young kids, it is inevitable that someone in a discussion like this will bring up small children. It happened earlier in this thread and I just chose to ignore it, and this isn't necessarily directed at you. Here are my thoughts. When discussing minors buying/being influenced, I'm considering teens. Preteens may have the means and opportunity to purchase(if it weren't illegal), but that would be uncommon, and parents should still have influence at that point. Children(younger than 12) should not have the means or opportunity to purchase anything that their parents would object to, but it is not society's responsibility to enforce this, though some may choose to do so. If it were legal for a 5 year old to purchase something, that doesn't mean the vendor has to sell it to them. My 5yo doesn't have the money to buy vape gear, couldn't get to the store by herself to purchase it, wouldn't be able to tell the shop owner what she actually wants, and wouldn't be able to provide the correct funds. She's not slow, she's just 5.