> Should be "You're thinking".
This should be "This should be 'You're thinking'." don't you think? Why bother correcting someone's grammar with a sentence fragment? You're just trading one mistake for another. I'm hoping someone finds a grammar error in my post, because continuing this would be hilarious.
> This should be "This should be 'You're thinking'." don't you think?
Reflexively, I think it should be more like ...
... but then that's just me, in [my] quirks mode.