> What part of... rules out aliens?
Because
1) Ruling _in_ aliens requires proof. Insisting that this specific scenario be ruled out is classic "shifting the burden of proof" https://en.wikipedia.org/wiki/Burden_of_proof_(philosophy)
The train of thought that "we don't know what we saw, so ... aliens!" is somewhere between wishful and nutty. Extra-ordinary claims require extra-ordinary proof.
2) claiming that it's _definitely_ "technology and flying at considerable speed without discernible means of propulsion" is itself a stretch. Given the supposed behaviour, a _very_ big stretch. More likely it's equipment failure, lens flare, sundog, bug-on-the-lens, etc.
3) the strong argument against this being real is how it is "perpetually liminal" https://news.ycombinator.com/item?id=27354021