That's possible, but I think it's more likely that the person is simply a rude, graceless person who was all too happy to take a few days' holiday letting someone else pick up the cheque /: OP says they paid for food, trips, activities, and their guest was all too happy to allow them to pay for everything.

If someone is very worried about projecting the wrong impression, I would have assumed they would make an extra effort to be polite. That's what I do - I don't think I have social anxiety, but I am very shy, and aware of coming across the wrong way. I think irl I am awkward, but I always try to be polite to try to make up for it. Tone can sometimes be hard to get right, but it's possible to imitate the ways other people speak and sort of 'fake' it so it sounds right...

Also, the person apparently wasn't so terrified they didn't travel all the way to the house of someone they've never met in person before to stay for days (I have done that and it is terrifying).