Yes, it can be. That's why I like to keep my two in a little one gallon jar. Then when I clean it, they are the only ones who need my attention.
They are air breathers, but they dehydrate very quickly. If they jump while you are cleaning, and if you notice them do it, you can scoop them up and put them back into the water, but if you don't see them and they escape, they will be in trouble.
I have the larger African Clawed Frogs too, and when I clean their tank, I cover most of the top and just leave an opening large enough for me to get the siphon and my hand and arm in.