Can be. It could also be a ellipse formed toroidal shape, or a regtangle, pointy triangle, and so on.
Speculation does not equal factual.
If you read the letter closely, they are consistently using terms like “assuming” and “going with this assumption”.
Everything is speculation.
The right way to move forward is to archive the suggestions in this letter in the back of the head, assume nothing as you collect more data. When more data has been gathered, and analyzed, one can pick up on the suggestions in this letter, re-evaluating the plausibility in the speculations stated in the letter.
If you assume a specific explanation, it is more likely that one would collect data and analyse it in a way that confirms the beliefs of the researcher.
Take the EM drive. Perfect example. Going with the assumption that it works, many teams failed to account correctly for thermal effects on the measurements. When that was corrected, the results showed that the EM drive would be orders of magnitude less efficient compared to a photonthruster. Basically a light-bulb.
So. Fine. Believe that Oumuamua is alien.
All I ask, is that you stop claiming a letter that speculates on possible origins, to be factual or conclusive. I isn’t.
As I have repeatedly stated, that the discussion in the letter is extremely interesting, but the authors have stated themselves that it is more likely that it is a depleted comet core.
So please stop saying the letter is stating reality.
It is not.