We can already do MWI vs Collapse without being clear on F=ma. MWI is not even considered because MWI does not output a string that begins with the observed data, i.e. MWI will never be found when doing Solomonoff induction. MWI's code may be a part of correct code, such as Copenhagen interpretation (which includes MWI's code). Or something else may be found (my bet is on something else because general relativity). It is this bloody simple.

The irony is, you can rule MWI out with Solomonoff induction without even choosing the machine or having a halting oracle. Note: you can't rule out existence of many worlds. But MWI simply does not provide the right output.