People are being way too harsh on MC.
You have to remember that everything; from finding out he has a aunt and cousin, finding out he not only has two sisters but all three of them are part alien, and that their living shared mother is both alive and fully alien. To then having his alien side enhanced, and learning that he and his sisters were genetically designed to save the species they never knew they were or even existed from extinction. And the reason his species is on the brink of extinction is because of an act of genocide by a different alien nation and species. All happened in the span of a few months. That'd be enough to overwhelm anyone.
MC feeling frustrated and trapped is completely understandable. No there's no one literally forcing him to do anything.
But he would be feeling a lot of guilt of obligation. He is the only one who can save his people. The only one.
So his options are, do nothing and condemn his people to extinction. Or go forward with the plan he's been thrust into.
That plan, riding of destiny and prophecy, carries to hopes and dreams of countless people.
Personally, I know the guilt of having done nothing, when I could have saved my entire species with minimal effort on my part and by doing something I'm otherwise already inclined towards doing, would eat me alive.
I think wanting to go back to earth to regroup, and mentally and emotionally decompress is more than fair and is a good idea.
Yes there are safety concerns on Earth, but those can be mitigated.
