Kevin O'Leary is now a traitor to the country.

I would consider helping "negotiate" a US takeover of Canada to be an act of war against Canada or a preparatory act.

Criminal Code section 46:

46 (1) Every one commits high treason who, in Canada,

(a) kills or attempts to kill Her Majesty, or does her any bodily harm tending to death or destruction, maims or wounds her, or imprisons or restrains her;

(b) levies war against Canada or does any act preparatory thereto; or

(c) assists an enemy at war with Canada, or any armed forces against whom Canadian Forces are engaged in hostilities, whether or not a state of war exists between Canada and the country whose forces they are.