IF YOU HAVE EXPERTISE, THEN CONTRIBUTE, DAMMIT: https://developer.gimp.org/core/wgo/
They don’t need somebody to tell them their site sucks. They need somebody to HELP them make it better, to DO the work that you seem to be implying is very easy! They’re literally begging for it on their website.
Don’t tell him that he can’t do something. Let him figure it out on his own.