Tony had seen weirder things, too. Not that this wasn't weird, but he'd seen it already and also ransacked it when it had been burning down. Once all the people were saved, obviously. But the tech supplies had been useful and better than anything the hotel had had at the time.
But yeah, seeing dinosaurs first hand certainly wasn't an every day experience and there was some majesty in it, along with some awe even for someone as occasionally jaded as Tony Stark.
A closed portal would be unfortunate but Tony was getting the feeling that even though he and Strange had messed with something, the hotel was really the culprit behind the results and it was, oddly, because of that, that he reasoned it more or less safe. Probably. "I don't think it'll hurt anything," he said after a moment of consideration -- where he also stuck his hand back through the portal and then out again, and it stayed as stable as it'd been a moment before.