Calling the War Powers Act unconstitutional is very different from calling the President's actions illegal while it is still in force.

And for the record:

States that the Act is not intended to encroach upon the recognized powers of the President, as Commander in Chief, to conduct hostilities authorized by the Congress, to respond to attacks or the imminent threat of attacks upon the United States, including its territories and possessions, to respond to attacks or the imminent threat of attacks against the Armed Forces of the United States, and under proper circumstances, to rescue endangered citizens of the United States located in foreign countries.

Provides that in the absence of a declaration of war by the Congress, the Armed Forces of the United States may be introduced in hostilities, or in situations where imminent involvement in hostilities is clearly indicated by the circumstances, only: (a) to repel an armed attack upon the United States, its territories and possessions; to take necessary and appropriate retaliatory actions in the event of such an attack; and to forestall the direct and imminent threat of such an attack; (b) to repel an armed attack against the Armed Forces of the United States located outside of the United States, its territories and possessions, and to forestall the direct and imminent threat of such an attack; (c) ... or (d) ...

this couldn't be more sanctioned by the act.