True enough, but I really don't like depending on closed source solutions for something so fundamental as getting my code to run on a platform. I feel like I am betting the future of the product on the future of this company. Of course, I am already betting on the future of iOS and Android, but I have a lot more confidence on those too than on RoboVM
On top of that, RoboVM uses its own LLVM-based compiler rather than Apple's. So if Apple throws us a new compilation requirement, similar to the requirement to provide bitcode for watchOS and tvOS, then we're stuck until RoboVM is updated. With j2objc, you're using Apple's compiler to produce the machine code.