I'd bet there is a very wide gray zone between the current situation, and a "planetsized wall of debris", which badly damaged SpaceX's bottom line.
And, in much of that gray zone, SpaceX could be the very profitable leader in a booming market for launching all the replacement satellites, heavier collision-"resistant" satellites, and debris-sweeping satellites.
This is a good point, but I thought the fundamental idea of Kessler syndrome is a cascade trigger point which rapidly and inevitably becomes the point of no return at which the effects become inescapable.
Guess: Doom-preaching scientists often have vested interests in preserving very expensive, hard-to-replace satellites - say, Hubble. Journalists know that "more doom" => "more clicks". Nationalists and military folks love to talk smack about other nations' debris-spreading accidents and ASAT activities. And the whole canon and mindset of Kessler-ology was established before SpaceX made launch (of replacement satellites) anywhere near so quick and cheap as it would be now.