Almost nobody can even agree on what intellect means or looks like, so the point is moot. Ultimately, if you're a politician who achieved high office and are a well known public figure then there's SOME skillset there.
Moreover, you're smart enough to know what's going on with politicians. There are 50 different groups all pulling in different directions on every single issue. Ranging from industry to lobbyists to local groups to political infighting to constituency issues to backers to everybody else. You say the wrong thing and you can blow up your carefully managed position which is why politicians worldwide (generally) try to say nothing at all while sounding like they've said something. Because politics is won and lost in committees and amendments and all that stuff that 99% of people barely seem to understand happens let alone pays attention to. Speaking to the media can only really damage you outside of the odd Goldilocks moment. So I'm not sure it's really a fair way to judge whatever intellect is.
Look at Diane Abbott. She's one of the most accomplished politicians of the 21st century, and now Mother of the House and millions of people think she's a halfwit. She went Oxbridge too.
Firstly, I don’t think Truss is stupid, for some of the reasons you’ve outlined, but I don’t think she’s intelligent through the prism of my own perspective and experience. I agree that different people have different optics when it comes to what constitutes intelligence (and that it is, of course, relative) but that doesn’t mean I’m not entitled to subjectively evaluate Truss’ based on my own.
I’ve not limited my perspective to the reasons I’ve cited (although they form a significant part) but even based on the justification you’ve provided for her responses to journalistic questioning she’s significantly less nimble on her feet than (for example) Cleverly or Hunt at not answering the question that’s put to her.
Judgement is a great barometer of intelligence, imo. It requires an ability to absorb information, weigh it up, and arrive at a decision that is likely to provide a desired (or at least desirable) outcome. It doesn’t necessarily avoid a taking of risk, sometimes great risk if the circumstances dictate, but it requires an ability to read a room intelligently and make effective decisions. Truss’ judgement has proven conspicuously and spectacularly wrong on numerous occasions, and that is accentuated by her terrible people skills, lack of emotional intelligence and complete absence of empathy. That cocktail manifests itself in a deficit of intelligence in my view.
So if I was going to pigeon hole her, I’d say academically quite bright (most likely) but so lacking in other aspects that could objectively represent intelligence that render her to be of very ordinary intellect at best. Certainly less intelligent than Abbott. I think she’s also probably a sociopath, but a relatively dim one. I did consider describing her as an ineffective one, but that would ignore the office she held, which would be unfair.
She clearly has something about her to rise as far as she did, but it isn’t intelligence, at least not from where I’m stood.