I believe he was in England at the time, agent for several of the colonies (1774). He had also pleaded with her to join him there. Like most of the other founders, other than Sam Adams, he was still against independence and thought it likely he would remain in London for the rest of his life as he saw himself most valuable to America in that sphere.
IIRC from other biographies, being pilloried to his face in a session of Parliament because he received and secretly shared another man’s correspondence was a conversion event that turned him from British subject to fully American. He knew we would always be considered and treated as inferiors to the lowliest Englishman. Australians still deal with that attitude.