I got just some questions to ask:
How did he even get to be SSG?
If i remember you need 6 sayans transfering all their energy to just one of them, in future trunk's timeline goku, vegeta, and all other z fighters (including the rest of the sayans) and if picollo died where are the dragon ball to resurrect them now? gone.
But then again there are the "new namek"s dragon balls and "our" vegeta also did get the ssgss form from training so... idk