My dear lady, there is not the remotest possibility that you could ever be my bugbear!
I have no idea who runs the website you mention, but The Oxford English Dictionary (TOED) - the 'bible' of words and their uses - offers the following definition of 'sit' used as a transitive verb (quote)...
"to cause a person to sit, to seat in a certain place or position"
We see this in everyday sentences such as "Sit yourself down" or "She sat the baby in his high chair."
That last sentence is in the active voice...ie the writer draws the reader's attention to the person doing the action...'she'. There is, however, no reason why the writer cannot put the sentence into the passive voice in order to draw our attention to the person having the action done to him...'the baby'.
So, what would the sentence look like then? Well, obviously, "The baby was sat in his high chair." We could, but do not have to, add the words 'by her'. By the same token, we could perfectly correctly write, "I was sat there (by the usher)."
So, Pingping, if you are in any doubt now, just compare how authoritative the website mentioned is as compared with TOED!
And there I really will call a halt!