You saying they never show up as if it's directly related to your challenge rather than the fact that they probably have a billion things they'd rather be doing than going to a conference and getting in an argument is pretty laughable.
No comment on the rest, except to say that thinking you could have someone kicked out of a conference for their tone is a bit funny. Felipe is abrasive (though not incorrect, in my view) and not someone I would like to work with but you are not winning any friends for yourself or the project with your attitude.
I'll say it again: Go to FOSDEM, go to the GNOME stand. I'll be near the stand most of the afternoon.
Pretty nice to judge people over the Internet, as said, try talking to me in real life, making a real judgement.