They are pretty safe. But, they have to take all the flavor out to make it gf.
I still went for the amazing sushi though. They used to have gf sushi, but they changed their menu. When I asked if they could make the sushi from the old menu, they said "the cook can make whatever you request." So, I explained that I didn't know what was in the old ones, but I wanted it. He said he didn't know either. "Ok, well what could I order (with gf ingredients) that IS gf then?" He just turned around and walked away mumbling. I walked out and have not been back.