dremmel rotary tool and grind the screw head off.
then the bowl should come off.
Try vice grips on the remaining screw. Use lots of isopropy alcohol on the screw , it is a great lubricant for this but it evaporates quickly. Lots of back and forth wiggling to let the alcohol get in.
edit. looking again you may not need to grind the head off. but lots of alcohol really helps. On the screw though, not drinking until the job is done.