Of course, the VPN could be the one doing the hijacking.

Well let's assume that he f.ex. has friends in several countries to whose VPN servers he has a direct unimpeded access (by IP, not hostname).

Would a trusted VPN help? Or would hijacking the traffic at the point of departure (his phone / the air) still manage to corrupt the payloads?

"So do you trust some shady foreign VPN provider more than your government approved ISP?" might return true from journalists in autocratic states that have a record of censorship, surveillance and imprisoning journalists.