No, trail identification algorithms haven't been created by anyone as far as I know - that's been the point of my posts... it's possible and shouldn't be difficult. As mentioned - for well over a decade software has been able to convert images of handwriting to digital text and even crack CAPTCHAs. It would be easy for software to identify which pixels fall in the path of straight lines within an image of deep space. It would not be CPU intensive relative to the other tasks of PI.
I'm sure incorporating the rejected pixels into the stacking process can be done as well. For example, it might store references for the frame number and pixel location of the rejected pixels - that info can then be referred to and excluded from the final pixel value calculation.
And after you remove this trail of pixels, what do you replace the data with? You need to know what the trail masked. You say it "shouldn't be difficult". I beg to differ.
There are only 60 satellites in this model. What you also are not taking into account that SpaceX plans to have 42,000 satellites in orbit, and there are 9 other companies already approved to deploy similar solutions in competition. Suggest you try building a larger model if you really want to understand the impact.
FWIW, If they were all black and 'non-reflective' you'll have to develop an algorithm to remove black trails and still have the same issue of replacing the data with the correct background. Of course, distinguishing a black trail from a mostly black background might be a bit more of a challenge.
Of course the impact to astronomers is only the beginning. It will impact any space initiative that will be headed to higher orbits because it will have to pass through this minefield of LEO objects, and the prospects of doing course corrections to avoid collisions both with operational satellites and with damaged or failed devices will quickly outpace the computational ability of on board navigation systems, or even groundbased radar and real-time course optimization navigation systems.
We do not have the technology or the political structures to manage this environment. I think there are much more serious things to think about then just our hobbies.