Not quite the whole truth, I think you're speaking a tad beyond your expertise. While you're right that transient science generally does short exposures (TESS is 2 seconds, Kepler was 6.5, LSST will be ~20 iirc), the vast majority of astrophysical science I've been exposed to (mechanical engineer at an astrophysics research institute), 10 or 20 minute exposures are more the norm. Especially when looking at faint objects.
Doesn't take away from your main point - astronomers will adapt. I think they're perturbed by this because Starlink makes their jobs even more complex, and thus more expensive. A cost that SpaceX doesn't bear at all.
I think astronomers have a right to be perturbed about Starlink et al. SpaceX seeming to not care about the effect Starlink satellites would have on astronomy is ridiculous. At the same time stupid mis/disinformation like this tweet is also ridiculous.
“Because of scattered light in the optics by the bright satellites, the scientific usefulness of an entire exposure can sometimes be negated,” AURA said in a statement last month. “Detection of near-Earth asteroids, normally surveyed for during twilight, would be particularly impacted. Dark energy surveys are also sensitive to the satellites because of streaks caused in the images. Avoiding saturation of streaks is vital.”"
https://spaceflightnow.com/2019/12/09/spacex-to-experiment-w...
That may have worked with analog film before we had satellites, but Starlink is just the latest and brightest addition to the sky that makes that an increasingly bad idea. Change is hard, but it's not that difficult.
Instead, AND a bunch of shorter exposures. Then, your streaks are not streaks, but a series of point sources that can be removed trivially.
If I poo in your front yard, would you be happy with me telling you simply "well you can just remove it, what's the big deal?" Or rather, pooing regularly somewhere on a lawn in a public park that you really like and visit daily.
If you're doing a narrow field long exposure with tracking, that will be problematic and you'll loose data. Most scientific observations don't do long exposures, especially measuring highly variable things like exoplanet transits.
It's more effective to stack a large number of short exposures for scientific measurements. It's much easier to eliminate noise because everything that is not noise will be transient for a single frame in the stack. You can also remove frames with things like satellites, clouds, or airplanes without losing much data.
Knowing the ephemeris of satellites also allows observations to time short exposures to avoid occultations. Astronomers have been dealing with satellites, clouds, and airplanes for a long time. Amateur astronomers might have a harder time with Starlink satellites but they will adapt just like they did with the ISS and Iridium.