No, it couldn’t. That’s pure misinformation.

Kessler syndrome is only a possibility in orbits high enough that atmospheric drag is negligible. Starlink, by design, is at an altitude where the atmosphere is still thick enough to bring any debris or old satellites down to earth in a timely fashion rather than building up like Kessler syndrome requires. (To be clear, the air is still so thin that you’d need sensitive instruments to detect it at all. It’s just enough to produce a tiny amount of drag, which adds up over weeks or months to lower the debris’ orbit so that it meets thicker air)

There are plenty of perfectly legitimate objections you can raise to starlink without resorting to Kessler syndrome