No, XT was not an alt coin, it was an alt client and the only fork was in code, not in the block chain.  XT had some very bad things and should not have ultimately been the client to run, but the thing Hearn was most wrong about was the suggestion that bitcoin needed a benevolent dictator, and a single group of programmers is not much better than a benevolent dictator, nor is censorship, which is exactly what Theymos was doing beyond his scaremongering.  Unfortunately, it seems all involved are focused on power and control (even if indirectly due to the corrupting influence of potential income) when bitcoin needs to be free and open.

ETA:  To be clear, if Hearn were suggesting a fork in the blockchain at 50% consensus or less, it clearly would have become an alt coin, and at the once tossed around 75% consensus, it would have been controversial, but if it would have sorted itself out and made bitcoin stronger.