I do not think that Mr. Horowitz jumping ship is a good metaphor. I think he stayed the course using any ship going in that direction. That "direction" is being a career Verbal Hit Man (VHM), making a living by smearing and assassinating the character of others. Louis Proyect seems to be of the same persuasion - the only difference is that Horowitz got hired by the right, whereas Proyect remains largely unemployed.
The VHM character is a well know fixture in the Eastern European history, especially during Stalinism - as many brilliant careers were made by smearing, backstabbing, and destroying others (cf. _The joke_ by Milan Kundera). The proliferation of these characters in the US is yet another example supporting the "convergence" hypothesis popular in the 1970s and claiming that the US and the USSR are "converging" to a single model of polity and the economy.
Wojtek