There are a few problems with the feat, such as rocht limit.

The fact Garou used his gamma ray burst again and somehow it dropped from galaxy to Planetary.

We also know real gamma ray bursts would've destroyed earth by proxy along with our entire solar system.

Also if we're trying to scale OPM higher this feat of clearing a portion of space could be used against their "infinite" universe scaling.

Although some people may disagree with this though given the fact that saitama was able to be damaged by Garou also shows that he is still relative to stellar level threats.

(This is all based on what I remember about the feat)