Yeah you cannot compile without inlining specific messages. You can disable inlining of #timesRepeat: at image level because we added it for fun to see if it was easy to do in Opal. Now all other optimizations were in the old compiler and are mandatories. However, you can now in Opal disable these optimized messages in a restricted area (such as a class and its subclasses).
To me, it is kind of a bug that we cannot disable those optimizations, we should be able to do it (so 1 day in the very very far future we could have the JIT inlining these control structure allowing us to implement all these inlined messages in all classes). But one thing is that some methods such as #whileTrue are not implemented in a way they really work (they have not stop condition, so if the compiler does not inline it, it gives you an infinite loop). Another thing is the interrupt point problem as Marcus said.
I don't think your other bug is related Opal optimization, only #timesRepeat: is new and therefore can be faulty (and in this case, the bytecode is correct, so I guess it is faulty because it removes an interrupt point).