After you have spent years observing people you realize that the majority of people do not do their own research. Stigma is mercy in this case. When you start trying to explain why someone shouldn't do something that is bad but complex to understand you lose people. Many people will never do their homework and only follow social signals. Calling them alt makes it sounds like they are just alternatives instead of what they are. Inferior copies at best and outright scams at worst. Many people have concerns about bitcoin. Most of these are just things with answers. They are suffering from ignorance. When they waste time with inferior coins or scams they seem to lump bitcoin into the same bucket and never actually learn.

Sometimes the trust isn't nice. But it is unkind to be nice sometimes. The truth is they are shitcoins

I can understand that, but there are 2 goals.

You have to understand your audience of course. While you might open on a newbie with "Oh don't go talking shitcoins here" (the social stigma) I would also say that explaining to them after the meetup or something exactly what the problem is would also be important.