That sounds like a good reason, but I still have two problems with it:
The number of observations like this is pretty small and I can’t see them having a huge impact on GBIF. There are more than 27 million RG observations which I assume are all sent to the GBIF, but if you look at Casual observations that are wild and have photos, there are fewer than 150 thousand of them. And this is still an overestimate because it includes observations that are casual because they lack locations or dates.
Surely these observations can be marked RG without them being sent to the GBIF. If GBIF doesn’t want them that’s all well and good, but marking them as casual on iNat just makes them incredibly difficult to find, and anyone who doesn’t have some experience with iNat is probably unlikely to find them and use them. To find those observations that I linked to above, I had to change several filters and manually change the URL, and I still couldn’t exclude observations that are marked casual because they lack dates or locations. It just makes these observations extremely difficult to find and use when they’re marked as casual.