This honestly doesn't sound like a dumb idea to me at all. Giving Java players with a certain rank (let's take Diamond+ as an example) something in return might actually be a great strategy to attract more players to the Bedrock network and make sure that a part of the Java players don't quit Cube altogether. It could be the lowest rank (at max) or a bundle or whatever (I'm not very familiar with the Bedrock store), as long as it doesn't cost a lot of money.
I don't think Java players are entitled to a rank so what
@Marieke2001 said is right, but let's look at it from a strategic perspective; handing out a cheap sort of 'reward' might convince Java players to switch to Bedrock, right?