> Can Apple just acquire the Beeper Mini team to stop this move?
No... the code is already released.
No, it's not because this isn't Beeper Mini. The op got the title wrong, and nobody is clicking the link and reading the readme in the source.
If code has been released as open source then the code is out there now. Seems too late to stop. I would also question if apple has any benefit in launching an android app. iMessage is interesting to apple as long as it forces people to buy apple products.