Plummet implies a straight-line dead fall, or close to it. It derives from lead weights (hence the similarity to "plumber") attached to a line, used for sounding depth of water or for marking a straight vertical line. The "verbing" of that noun and its figurative use to describe falling appear to be quite recent developments—Webster's 1913 only lists a noun. I'd say it's the wrong word for this case, but then I'm an opponent of using slightly-similar words interchangeably, such that we effectively have fewer words to work with. However, I'm losing that fight anyway, so who cares I guess.

[EDIT] On reflection, this is even goofier than I thought at first, since the choice of lead for those applications is precisely because it's little affected by wind, and even fares better than most things against moving water, while this is entirely about something falling faster because of its interaction with air.

I don't see why it is a dumb objection. Word choice is important, especially for journalists trying to convey information to the general public and even more so when it comes to headlines - as the majority of people won't read the article to understand the nuance.

I genuinely think a decent number of people are going to envision a situation where satellites suddenly plunging out of orbit like they would in some big budget disaster movie. You are well within your right to tell them they are thinking of the word "plummeting" incorrectly but you are fighting an uphill battle. Technical and dictionary correctness has its place but to convey information properly people must consider the vernacular.

The definition of the word, that everyone is probably familiar with, strongly disagrees: https://www.merriam-webster.com/dictionary/plummet

    Plummet:
    
    1. to fall perpendicularly
    
    2. to drop sharply and abruptly

Or, Google's scraped definition from Oxford dictionary:

    fall or drop straight down at high speed.

If you google "satellite plummeting", you'll notice that almost all of the results also include "fireball", "burning up" and/or "reentry".