He is a terrible poster, but he's not wrong that sex is absolutely more integral to furry conventions than corporate conventions. They sell sex toys to one another, hold panels about their kinks/fetishes, organize rooms for orgies, openly walk around in fetish gear, all while dressed as animals which have dozens of pieces of yiff smut drawn of them; it's one of the primary appeals (hence the presence of STD testing, because they're there to fuck).
Also, you typically won't have minors at those corporate conventions. You can be a minor today, register to be a panelist on an 18+ panel at the biggest furry convention on Earth, and so long as you turn 18 years old by the day of the panel, it's A-OK with them. Are you 17 years old right now and want to give a panel on the ethics of murrsuiting? You can schedule it today for the last day of the convention, be 17 years old for the first 3 days of the convention while advertising your 18+ panel, turn 18 on the last day, and then host that panel.
Furries assuring one another that it's not actually a problem doesn't make it
not a problem.
The only reason anyone even cares about sex at furcons is because of the costumes. Remove that element and no one would think twice about furries fucking.
Yeah, if you dress up like a cartoon animal mascot, invite a bunch of people whose one underlying quality is that they all jerk off to cartoon animals, specifically include minors in your event (sometimes younger than 13 years old), and then have a bunch of group sex together, people are going to think that shit is weird.