Incorporating RCS messaging for Android on iPhone can compromise my security?

I don't think you actually understand what RCS is.

On your iPhones message app, you can send either iMessages (blue bubbles), or SMS text messages (green bubbles)

SMS text messages (SMS = Standard Messaging Service) are actually very unsecure.

For example, since SMS messages are actually not encrypted at all, anyone with a mini cell tower can pick up text messages being sent and received in that area, and read them without issue since there's not any encryption (this is just an example of how it's not secure, not saying this is actually happening to the average person)

RCS text messages (RCS = Rich Communication Service) is simply an upgrade to SMS which does include proper encryption (Since Google has stepped up and streamlined RCS and made the new standard)

It will be very similar to iMessage (iMessage will still be better), and will allow you to send high quality pictures, video, see typing indicators, read receipts, and most importantly encrypted messages. Apple has since confirmed all of these features as well!

Apple also stated that it will be working with GSMA, and Google to improve the encryption on RCS as a whole.

TLDR: You have absolutely nothing to worry about, this is literally just going to add more security to your phone AND improve your texting experience with anyone who doesn't own an iPhone :)