Because for years he was a member of "the loyal opposition" and tried to be humorous and reasonable in his disputes.
   This issue has gotten awkward and divisive and made folks say things in ways they 'may' think better of later.

It is hard to tell in this virtual medium exactly what is in someone's heart.... I hazarded a guess that the specter of losing after 8 years of winning has been hard to take and made friendly banter difficult.