The content is being uploaded to Adobe’s servers, they likely have the right and may even be legally required to moderate it to some degree.
This yet another reminder that the cloud is just somebody else’s computer. Somebody who might want to impose some degree of control with what is done with their computer, for whatever reason.
I’m guessing RCS support will be as barebones as possible while still technically functioning. All of the fancy bells and whistles will remain exclusive to iMessage.
Some iMessage features might not be possible to implement with RCS I suppose. Maybe RCS messages will get a different colour. All Apple said in the WWDC keynote was RCS would be supported, they didn’t elaborate any further.