English isn't his first language. It can be really tough to express yourself in another language unless you're constantly using it and surrounded by it.
I bet my French makes me look like a retard to French people.
My ENTJ friend speaks English very well, but has lived in Russia for most of his life so when he sends me emails they are very simple and often misspelled, even though he's extremely intelligent. He speaks better than he writes.
"Sentiment without action is the ruin of the soul." - Edward Abbey
I wouldn't recommending touching an ISxJ you don't know well unless they've allowed you into their personal space.
...it might weird him out - not because he is weirded out by her personally, just because it's perceived that any strange person who does that is being overly familiar.
Yeah. That's true for me. But it's only a bad thing if I don't like you. If I do like you, you'll see the surprise and discomfort at first, but then mixed feelings and maybe enjoying it.
So I think his reaction would give it away, yeah, and it wouldn't hurt to test.
But that's just one option. I know that may not be your style at all.