Hi! That's actually a good question, it would be nice if it worked for disabled choices too.
I just did some tests and whenever a button has the sensitive False property, the Ren'Py tooltip will not display. I think this is because insensitive in Ren'Py affects more than just the styling, making it so the user can't interact with the screen element at all (so it can't run an action, display a tooltip, etc) .
The easiest fix I can think of is to circumvent the sensitive button property and instead make it look disabled (and make the action do nothing) if the player fails the check. In my test project it looks the same as an insensitive button but does display the tooltip.
Replace the textbutton part of the screen code with this
You may want to play around with the disabled button styling based on your set up and whether you're using a "gui/button/choice_insensitive_background.png"
There might be a more elegant solution, but I'm not aware of it. Let me know if this works for you!