While that is potentially true such micro missiles tech currently doesn't exist and modern Russia doesn't exactly have a track record in developing such tech.
In addition, its far harder then you would think. Each such missile would still need complex computer system and propulsion hardware and so on. It would be cheaper then a Starlink sat but not by that much.
Also, even if you assume 1/10 the weight, SpaceX can easily launch 10x more then Russia can. With Starship coming online SpaceX by themselves can launch 100x what Russia can.
And of course if Russia did such a think SpaceX would have US government support.
> After that… I imagine it’d become impossible to launch anything ever again.
I do not think this is actually true. The decay is to fast on this altitude for this to actually happen.