I understand your point, but a couple of thoughts:
Do we accept Walker as a true conservative just on Trump's say so? Of course not having a political c.v. may be an advantage.
It is interesting that Gary Hart and John Edward's predilections would not be a disqualified in todays political environment.
True- i dont know much about him other than what ive heard him say- he “sohnds conservative”. But we certainly have been fooled many times before