@BCj You're missing a step here
You can edit the RTP and use the edits in a commercial game without problems.
You can also edit the RTP and give the edits away for free to use in a project, no matter if commercial or not.
What you cannot do is sell edits for use in another project, no matter whether that project is commercial or not.
And there was probably some mixup earlier with these resources that made it easier to simply forbid commercial use than to un-tangle the mess for this specific case.
But other edits have been allowed free use for commercial projects, this is a special case where the artists don't want the edits used in commercial projects. Because that is always the decision of the artist, to allow or deny commercial use on edits he/she did.