I think you're talking about two separate things, it collapses when you tap because… well that kinda makes sense, there's a button to tap to collapse on the website so I just made the tap target bigger, there's not much else use for a tap. The second thing where slow scrolling can register as a tap and thus collapse it… yeah that's annoying as hell, I know what you're talking about and I'm working to fix it.

I use this feature all the time. I collapse comment chains I'm completely uninterested in by tapping on them.

That said, you can turn it off for comments:

Settings > General > Tap to Collapse

Thanks. I like it too. It’s just when reading a long main post I find myself collapsing it on accident