I agree that the article starts out needlessly inflammatory. There are big egos in Science, as in all other endeavors, and folks can get reactionary and arguments heated. "Science advances one death at a time" after all.

That said, further down the article, there is some legitimate discussion about alternatives and even mention that "Wallace Broecker—the scientist who proposed the conveyor shutdown hypothesis—eventually agreed with the idea of an extraterrestrial impact at the Younger Dryas boundary, and thought that it had acted as a trigger on top of a system that was already approaching instability."

I can't say whether an impact happened for certain or not. I await further evidence. But I do think that the hypothesis is plausible and it's clear from the Chicxulub impact that meteors can have disastrous impact on global ecology.