Your error is a java error and as such unrelated to openHAB in the first place.
OpenHAB runs on Java, so in principle yes it can run on PPC.
But is it a good idea? No. There’s likely noone but yourself who ever tried, so there’s all sorts of yet-to-be-discovered bugs and you’re totally on your own here.
Just adding a few keywords to this discussion so others will find it through search:
Running OpenHab on Apple Macbook G4 with PPC32, PPC, PPC 32bit, PowerPC using Azul Zulu JVM.