No, I can't see how this puts the children first.
Especially as the policy isn't in action yet, and he's just guessing what might lie in the future for his school.
A very premature gesture, and only a gesture, that takes an apparently successful teacher away from his school when there isn't even a glimmer of a timetable for its conversion.
MATs aren't inherently wrong-headed, so perhaps there are already irons in the fire locally already and he knows he cannot work with the lead candidate? In which case, he should perhaps have said so, but of course that would a) be unprofessional and b) be unrelated to latest policy announcements.