I think you perhaps misunderstand he psyche of a lot of Evertonians. We literally hate our own players. Maybe not all of them all of the time but by and large each player will be roundly detested by a significant portion of the fan base. Even our own youth products. Barkley, Tom Davies, Rooney (technically he was a youth product) Calvert-Lewin etc.
See it as Tosun fitting right in. There's no need to Martyr him. Honestly. Check out the utter dismay when we signed Martina from Southampton and Williams and Gylfi from Swansea. Our own league. Everyone's rubbish, we like no one. Don't flatter yourself. Turks aren't rubbish enough to stand out as particularly awful. Feel better now?
Then you forgot what is to be fan of a team (I am aware this statement is quite arrogant).I am supporting Cenk not because of I am Turk (for god's sake I am Lazuri which is a minority at Turkey) but he is an ex-Besiktas player. For the same reason, I support Everton. You may think these two things may not converge but (at least for now) they do.
When you look at squads, there is no reason why Everton cannot be fifth. I think the problem is about Sam.
And you should know Cenk is a winner, he won Championship when Besiktas was not allowed to make transfers because of financial fair-play; he and his mates won the title against all odds.
Believe in him and his personality, if not; send him back mate. Just don't write his name in the same sentence with Martina; it is a major insult.