You really do not understand the point of “at-will” employment, do you.
No. Employers do not truly need a reason. And before it begins, I will not have a back and forth argument regarding this. It is a fact of working in Corporate America…they can terminate you and your role anytime they wish with very little recourse. If you are lucky enough to be in a union (which is NOT at will employment) then it is a different matter.