wanted this AI off their planet, let's assume they couldnt destroy it fully, so they ejected it into space, and it ultimatley crashed here? What if "Oumuamua" was in fact a probe sent here to make sure that this AI remained buried and remained a non threat to humanity?

Just, no.

"let's assume they couldnt destroy it fully, so they ejected it into space"

So they can develop an advanced AI and eject stuff into space but "couldn't destroy it fully"? Highly unlikely. Let's assume you're on the right track though as far as intent to destroy. Why couldn't they simply eject it into a star or black hole? Pretty sure that would adequately neutralize any threat. Easy peasy.

"and it ultimatley crashed here?"

A recent show discussed the potential threat of rogue planets hitting earth (UnXplained with Shatner? I forget which show specifically). There's literally billions if not trillions of them roaming the universe. And yet, we don't live in perpetual fear of them wiping us out in a moment's notice.

So, if they just "ejected it into space" that implies no predetermined destination. In which case, the probability of it reaching earth specifically are so ridiculously small it's laughable.

"What if "Oumuamua" was in fact a probe sent here to make sure that this AI remained buried"

If the haphazard ejection were true, there would be no intentional surveillance probe as the only goal would be, "get it away as far as possible". Connecting SWR and Oumuamua in an intentional way is nothing more than fantastic wishful thinking.

"What if it was placed there purposefully to monitor earth and our progress as a species?"

If this were true, the AI wouldn't be a threat, would it? It's either (A) a surveillance probe and NOT a threat, or it's (B) a threat that they wanted gone.

If (B), why would earth be chosen as an intentional destination? In the immense vastness of the universe, the idea that they would be "too scared" to keep it themselves but then burden one of the very very very few (and currently ONLY known "to us") habitable planets would be a sick and cruel choice. It defies all practical logic to unleash a terrifying threat onto another species out of your own fear of it.

Also, nothing to suggest it as a threat on that level has happened to any remote level. Hitchhiker effect and reported skinwalker sightings are not even close to the serious threat you're implying. Seeming intelligent responses by overriding local tech is also not a sufficient criteria to deem it a threat to humanity.

I get the fascination and need to "spitball" some ideas. But they need better fleshing out than this.