No upstream commits is not a reason to delete the packaging, especially if the source is still available and still builds. Orphan it if you aren't using or interested in maintaining it any more.

On Mon, Mar 9, 2020 at 8:56 PM notify--- via aur-requests <aur-requests@archlinux.org> wrote:

sum01 [1] filed a deletion request for ruby-htmlbeautifier [2]:

This project has seen zero commits since 2017.

[1] https://aur.archlinux.org/account/sum01/
[2] https://aur.archlinux.org/pkgbase/ruby-htmlbeautifier/