Is calling Theresa May a stupid person better than saying she’s a stupid woman?

There’s something about the ‘stupid woman’ controversy I am not getting. So, it’s fine to call someone a stupid person, but not fine to call her a ‘stupid woman’? It’s the qualifier, the adjective, not the noun, that makes the remark rude, though in the case of Theresa May I think Jeremy Corbyn is merely making a truthful observation, whether the noun be woman or people – as he maintains he said. Would it be equally problematic for Mrs May to call Mr Corbyn a stupid man? “Stupid” may be unparliamentary language, but I can think of a lot worse. She is a person, certainly, but she is also a female person, a woman. Therefore, if she’s stupid, she’s a stupid woman, no? Mr Corbyn has said he is “opposed to the use of sexist and misogynistic language in any form”. So we can only use the word woman if it is qualified by a positive adjective? That’s nuts.