Welcome to the forum
@forageandforge.
Unfortunately, your question kind of answered itself - the creator told you point blank it wouldn't work, and it doesn't. There may be a compatibility issue in the game with newer versions of the engine, but more likely the Wii is likely just running out of memory. It only has 64MB, and a portion of that of that goes to running the operating system.
Every OpenBOR module is different and has different memory needs according to the creator design, scope of the game, and so on. Some games modules are just too big for a console like the Wii to run at all without severe cuts. Some game modules could fit, but their creators don't care about console ports, so they choose to load everything right up front to eliminate loading pauses between areas. I don't know which case it is for Rescue Palooza, but either way you're out of luck for now. It's possible the creator will release a cut down or load staggered version for the Wii, but that's entirely up to them.
I can also try using my PS2
You can forget all about running it on the PS2. There is no port of OpenBOR for PS2 at all, that's the original Beats of Rage engine, not OpenBOR. The PS2 has even less RAM to work with and a Silicon Graphics based architecture that makes porting PC applications extremely difficult.
Sorry I couldn't offer you more, this one is just meant for PC.
DC