Your analyse for relegation is good but it will be very difficult for Gum to save himself.
He has a loss more than Suikerboy and have to recover 103 pts with suikerboy not to be relegated.
Suikerboys should lose with a big gap and Gum should win with a big one.
I think you mix up their point difference :)
BC Gum has -104
suikerboys -207
So with BC Gum +1 point difference win and -1 suikerboys loss, it's Gum who saves himself.
Or am I missing something?