Harvard professor Avi Loeb has found fragments of a meteoroid that he believes could be from a spacecraft from another civilization or some technological gadget

Even in his own words on his own blog, he seems to positively believe that they're from aliens.

The magnetic nature of the spherules implies that we do not need the sluicing device and can continue using the magnetic sled for the coming week. Finding more spherules will allow us to pinpoint the meteor path and potentially seek a large object that may represent its core at the end of the path. If such an object is retrieved, its structure could inform us of its technological purpose and design.

This paragraph is the first mention in his post about anything like aliens, and he seems to just assume that these metal balls came from/with a core and that that core has a technological purpose and design. He doesn't seem to be saying "alien origin is a possibility" but taking that assumption entirely for granted and leaping many steps further ahead.

Combined with the last two paragraphs:

As the philosopher Arthur Schopenhauer noted: “All truth passes through three stages: First, it is ridiculed; second, it is violently opposed; and third, it is accepted as self-evident.”

Gladly, the discovery of IM1 spherules of anomalous composition moves the discussion to the third stage. Given that, some colleagues might add another stage: “… and fourth, I said it first.”

It doesn't exactly paint a picture of whimsical wondering to stimulate the imagination with the remote chance of something world-shaking. The world-shaking is just being taken as a given when all he has so far is "we found some weird alloy in that interstellar rock that doesn't match our home system's rocks."

He's not just some random, crazy professor, either. He was chair of Harvard's astro department

I'm not familiar enough with astrophysics to provide any commentary on the field, nor can I state anything about Avi Loeb in particular, but sadly I have seen a number of other fields allow people who produce questionable research to rise to the level of "prestige" in those fields.

My criticism comes specifically from the perspective of a statistician. Note that I am limited in what I know about any given field (outside of statistics) so of course take my opinion about researchers in those fields with the appropriate grain of salt, but I do feel comfortable criticising a researcher's use (abuse) of statistics when making a claim and boy are there some whoppers floating around (again, not necessarily with Loeb-- I haven't read any of his actual published research). While this does seem to be more common in the humanities and social sciences, STEM/"hard" sciences don't seem to be immune. I don't know how much of it is intentional p-hacking and how much of it is just stupidity, but bad research is everywhere-- even the highest places-- once you start looking for it.