They're probably right, depressingly.
I can't make anyone else leave, but I did what I could by leaving personally. I am generally enjoying the experience over here more anyway, so I am not missing a whole lot. Maybe a couple niche subs, but I was considering working on launching equivalent communities over here.
Honest question, why keep quiet? I assume they are aware of the shit that went down in Reddit, if you provide Lemmy as an alternative some may actually try it and end up liking it more. The more people swap over the more it becomes an attractive alternative for others.
You don't have to be obnoxious about it, but just a suggestion could interest them.