Sorry for the delay on the answer...
After your last comment I took the opportunity to double check it, and yes, the followed approach was preventing the overflow already, however and in order to ensure it we add a new selector based on the "ptr-refresh" selector which is added to the body when the PullRequest animation is enabled in order to implement the overflow hidden to the main content as you suggested.
Let me also share that this latest update will also be available on our next month release.
Once again, thanks for your feedback.
Cheers,
JR