Not quite - this is only true if you discount the outgassing hypothesis entirely & assume that all of the acceleration is from solar radiation pressure. There is at least one good recent paper strongly advocating for outgassing as a more realistic (if less exciting) explanation: https://www.darrylseligman.com/oumuamuahttps://arxiv.org/abs/1903.04723
Thanks for the link. The difference between the paper from the two physicists I linked to, and yours, is the assumption of outgassing vs an assumption of solar radiation pressure, as explanations for acceleration.
I have no idea how plausible the assumption of outgassing is in which you linked, as it is qualified by additional necessary assumptions to explain why no outgassing was observed (from the paper: venting which migrated to a non-visible path). Is that assumption more likely than this object just being a thin slate of rock? I guess, anything is going to be more plausible "than aliens, until its aliens."
I've been following the papers a bit, but I'm also not an expert in the field, so I likewise have a hard time assessing the plausibility of outgassing given the lack of an observed coma. I can't find a reference, but I seem to recall reading that there are still possible (though implausible) scenarios (depending on grain size & albedo & lots of other variables) where outgassing could be significant enough to produce the observed "thrust" but not enough to be visible in our scopes. Of course it could also be a combination of outgassing and solar radiation.
I will say though that physics people I've spoken to about it are much more skeptical of the solar radiation hypothesis, simply because radiation pressure is so weak. I'd be surprised if it were a thin slate of rock as the dimensions are so outlandish compared to anything we've ever observed, plus I would think be there might be "structural integrity" problems with an asteroidal body that thin and sheetlike. The "solar sail" calculations done by the folks linked to above may also assume/require that the sail "turns" itself somehow to constantly face the sun, since the observed acceleration vector was entirely pointed radially away from the sun.
I have heard one radiation pressure idea that I liked, though, which is the "dust bunny hypothesis". If 'Oumuamua were, instead of a solid body, more like a very loose, fluffy agglomeration of dust, it might just have enough surface area for us to see it (and to be hit by enough sunlight to get a push), while also having a low enough mass to produce the observed acceleration. IIRC this may have other problems, though, eg. requiring the dust to be super-high albedo for it to be visible. Seems like there aren't any "nice" answers left, so sifting through the "least improbables" is pretty difficult :)
> more like a very loose, fluffy agglomeration of dust, it might just have enough surface area for us to see it (and to be hit by enough sunlight to get a push), while also having a low enough mass to produce the observed acceleration
Wouldn't that be a great cloud to surround your spaceship with. If you have some way to generate artificial gravity, this would be a really advanced alien stealth technology.
You'd still have the mass of the spaceship to accelerate. The point of the dust cloud hypothesis is that it works if the whole thing is very light.
If you have a spaceship inside the dust cloud with its own means of propulsion, you don't need the dust cloud to get the same effect. Just use the propulsion and paint the spaceship white if you want to reflect a lot of light, or black if you don't.
But then the shape of this light-absorbent object would be resolvable. If you surround yourself with a cloud of absorbent material, you get "plausible deniability" to your expedition.
When you're asked, "hey were your forces in our solar system", you get to say "are you sure it wasn't just a cloud".
I read so many theories on it, it's quite fascinating. Just search HN for Oumuamua.