As to not startle her, Battler doesn't use his magic to enter the cafeteria. To get the entrance, sure. However, after that, he walks around a bit, scanning the area for any signs of the body that he had witnessed his aunt in over the computer.

... Needless to say.... that was quite the unique introduction to coming to this foreign tower. In fact, running into a culprit version of himself was quite the surprise.

Once spotting her, he approaches the table, waving a bit as he pulls out the seat across from her. "Yo, Aunt Rosa. Long time no see!" He says with a big grin. He was always one to want to lighten up the mood.