Alaska flight crews are very consistent in announcing that the First Class lav is reserved for First Class passengers unless the aisle is blocked by carts. And, contrary to the gentleman’s claim, no Alaska aircraft has two lavs up front. Most have three aft, which typically allows a line of eight people to move very quickly.
As for whether the forward lav was empty, I don’t take any claims seriously from someone whose claim about the number of lavs was inaccurate.