I would just advise them to add a small sticky indicator that there is more content below the fold and then hide the scrollbar as a fix to the UX issue, like I mentioned before. That may not be neccessary in every case, but in the one you showed, it would be rather useful.
Maybe some light inset shadow with js? Or a very thin scrollbar using pseudo selectors...
Or clip some content in such a way that the user would know there's scrollable content...
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I would just advise them to add a small sticky indicator that there is more content below the fold and then hide the scrollbar as a fix to the UX issue, like I mentioned before. That may not be neccessary in every case, but in the one you showed, it would be rather useful.
Maybe some light inset shadow with js? Or a very thin scrollbar using pseudo selectors...
Or clip some content in such a way that the user would know there's scrollable content...