i thought starlink was using a low orbit that separated it from most other objects and would cause relatively rapid decay of debris. are there other objects in that orbit we should care about?

"developing a new anti-satellite weapon" seems a laughably overblown description, when the supposed weapon amounts to little more than a box full of BB's, with a couple sticks of dynamite in the middle to spread 'em out in orbit. If they had a suitable rocket ready to launch, then a good-enough warhead could probably be designed from first principles, fabricated, and launched within 24 hours.

But from a Russian PoV - considering such weapons, and leaking that fact, could be an extremely cheap and credible method of sabre-rattling.

(Vs. actually using such weapons against Musk's constellation would be a clear attack on America's interests and capabilities, and would draw a very harsh reaction. Outside of WWIII or WWIII-lite scenarios, it'd be a Bad Move.)