I'm not entirely sure how much of a hand he had in the creation of the cybermen here, and how much of it was just witnessing their genesis, as he says.

I guess we'll find out, hopefully with how he ended up there in the first place, because I can't see the Master volunteering for eons of watching Mondasian settlers live and die and then decide Cyberfication is the solution, all in the disguise of a dim-witted sidekick. Usually if he is behind something he is so in a leading position, a chief scientist/advisor/Prime Minister. His vanity rarely allows anything else, Crispy!Master excepted who had nothing to lose in that department.