Well, that confrontation has ended, but clearly the guildmaster is not done yet since he's still controlling the guild.
With that said, now that Yuuta has displayed his power so prominently, adventurers will go around and spread the word that he never was a conman but a real, and extremely powerful, spirit mage. Even people who aren't adventurers, who are trying to get to the guild or just passing by, will see the thorny vines around the building, ask how that happened, and learn of Yuuta. I doubt the guildmaster has enough control over all the adventurers in order to put a gag order preventing knowledge of what happened to spread; there are no doubt adventurers who were present who have friends who were not present who will definitely warn those friends to never cross Yuuta.
I don't think the adventurer guild will invalidate Yuuta's guild card. Right now the guildmaster is still being pressured by powerful people to get more rare materials from floor 50 and further, so if these people learn that he's blocking access to the dungeon from the one person who can get the materials the people who actually want the materials (and aren't interested in just speculating on its price) will definitely get mad. And of course, I'm not sure anyone can actually prevent him from going inside the dungeon; whoever is overseeing the card inspection would turn a blind eye, in fear of getting a bad end. In fact, since he was able to provide more fresh materials when there was a blockade in place on the 49th floor, even if Yuuta never actually bypassed the blockade, they could state that he has some spirit magic means of getting inside and that they never saw him go in.
Invalidating the kids' guild cards on the other hand... That's something the guild could do since since the orbs track mana signature based on ID, they might be blacklisted everywhere. But honestly, trying to enrage Yuuta when you don't even have a way of stopping him from retaliating with a room filled with adventurers is something very stupid to do.
Back to the wait for more.