"Speaking about your size, we're going to keep you here until you return to your original size... just in case." Not that she doesn't think the potion will wear off, but it's in the off-chance that it didn't. Safer to have him in the hospital where he could be monitored and any potential complications be watched than potentially outside and ending up lost. She's sure people would do their best, but accidents happen... also, Gokudera.

Looking over to Uraraka, she nods. "Yes, you managed to do that in the first attempt. Excellent work."

Which, yes, meant she prepared the room for little, but better it didn't come to being necessary.