As I wrote earlier, I don't think the two creatures feel like even vaguely linked, biologically, but as all we have are hints at what the basic idea is, I would have to hear the whole concept before just dismissing it, out of hand.
If someone told us that the Alien changed from chestburster ointo the thing we have come to know, a lot of people would have probably thought that was illogical, too, but it worked by being placed in the right context.
As for bitterness, no. The guy was invited by the questioner to explain what went on and he evidently had no problems with revealing it. That interview goes a long way to showing they are someone who managed to weather a lot of what Hollywood threw at them, in general, for several decades and survive.
Very intriguing.
