Shumer and McCain did manipulate him, because, through the committee and Senate votes, Rubio was the face of the immigration bill on the news programs.
Shumer and McCain though the new face might help them get it passed. They used him and he let.
Rubio was a collaborator, not a victim of Schumer and McCain.
Rubio wanted to be the face of that Gang of Eight bill.
Just because Rubio was useful to them doesn't mean that he was their unwitting dupe, Rubio's immigration agenda is identical to Schumer and McCain's. People are giving Rubio too much of the benefit of the doubt in claiming that he was deceived and manipulated by Gang of 8.
And if it really were true that Rubio was "manipulated," being that gullible and opportunistic would make him even less fit for high office than if he were sincere about it.