This is like saying Americans are empirically bad at soccer.
First, so what? Second, he should be smart enough to realize this is a rash generalization, regardless of past data. Third, he should know that saying something like this just insults those already in the field, encourages ignorance from others, and discourages those coming into the field, and thus serves absolutely no purpose.
For someone who is supposed to be an intelligent and capable leader of a heavily funded public project, this is pure stupidity and justifies any action they took against him, regardless of gender politics.
That said, the guy is totally sexist. No idea why BBC bothered to put it in scare quotes, when it's unquestionably true.