Well, the British in the 1770's weren't the Saddam Fedayeen.
They didn't commit the kind of atrocities these people are committing; in fact, they probably directed fire AWAY from Molly Pitcher,
Doubtful that the British knew they she was there. I note that Margaret Corbin, another woman who took over at a cannon for her fallen husband, was wounded at the Battle of Fort Washington.
In any case, in 1720, the British would have hung pirates Mary Read and Anne Bonney, except they were pregnant. I doubt the British had any compunction about killing woman, who happened to be in combat.
Indeed, doing a little research just now, I found that a number of woman fought the British and were killed by them in the Wexford Rising of 1798.
Bracketing a willingness by the British to kill woman in 1720 and 1798, I doubt that they would have had any compunction against killing Molly Pitcher.