There was hardly any surprise to begin with. Even if they don't go with the triple slave forms, Fubuki is definitely the type to reward Yuuki just for helping out with training, and Tenka is going to jump in regardless.
Can't help but feel that Fukuma's choice to impersonate Bell is going to turn out to be a massive fumble, and Ren's assurance that Bell can take anything the corps' training can dish out is going to backfire hilariously on her.