I will chime in with PaulK with the same conclusion: Most evolutionary pathways don't involve extinction in a single generation unless a series of concurrent beneficial mutation occur.
What we have is an extremely rare case of selection (HIV multi-drug treatment) that has been generalized to all of evolution. It's like saying that if you hit a wall going 3,000 mph in your car you would die. Therefore, all car accidents are fatal. That's the logic of Kleinman's argument.
In reality, a lineage of scaled reptiles does not have to acquire multiple mutations in multiple genes all at once in a single individual in a single generation in order to evolve feathers, contrary to the claims of Kleinman.