Disabling Autofilter menu Sort Ascending/Descending commands

Hello dear Excel Experts!

I want to restrict access to the sort features in Excel to select users.

I already implemented some RibbonX repurposing via CustomUI14.xml/CustomUI.xml like so:

Please Login or Register  to view this content.

Plus the following macro:

Please Login or Register  to view this content.

HOWEVER, I found that this doesn't disable the most important culprit for accidental sorting, the menu item when you click on the little AutoFilter selection boxes:

\1

Does anybody know how to repurpose/intercept these two? They don't seem to be handled via RibbonX...

P.S. Yes, I know that I could also protect the sheet and just enable all features (or most features) apart from sorting but the constant protection/unprotection that would need to be performed is really clunky and impossible on shared workbooks.