Time spent discussing stuff with Marc strongly suggest to me that interpreting Traveller RAW -- Rules As Written -- is unreliable at best. Traveller was Gee-Whiz 1970s Pulp Science Fiction Gaming in the Far Future, not Lawyers in Space.
Marc's comment on the Heavy Laser* solidified this in my mind just this month. It brought all the rules-breakers into focus as tests and features, not bugs.
Rules are guidelines whose boundaries were regularly tested (bent or broken) by most or all of GDW at some point. Alternative rules sprung up; some of them did so without invalidating old rules, even though they mismatched. This happened with setting and mechanics both. You know them yourself: ANNIC NOVA, mass versus volume, fusion rockets versus maneuver drive, High Guard, the AHL + Merc cruiser and orthogonal-to-thrust decks, advanced chargen, the Original Imperium, the Gazelle, every game module, Striker, and the beat goes on.
I might make the case that MegaTraveller is proof of the malleability of Traveller rules. It didn't start over: it mashed Classic Traveller together in a specific way, but certainly not the only way. You might say that Traveller4 is a different mashing together of Classic Traveller (and T5 after it). TNE was GDW saying that Traveller's core needs to be Twilight:2000, and it didn't cause them pain, because they continually invented ways of doing things as a company. I'm going on a tangent here, but you get my drift. That suggests, maybe, that even Traveller: 2300 didn't start out as a marketing ploy.
I suggest that this casual use and abuse of the rules included corner cases they didn't include in the rules, perhaps because they hadn't thought of it, or perhaps because they were fine with whatever. For example, I suggest that they either didn't think about empty hexes, or (more likely) they just hadn't thought through all the angles and so left it unsaid (e.g. calibration points and deep-space things in general.). I've seen this in Marc: he knows there's a topic that will require a book of thinking, and he doesn't have the time to think it all through, so he defers it. I bet he had to do this back when this was his job. That's part of the reason why nowadays he takes YEARS to finish something: he wants to chase some thoughts down more thoroughly. Oh yes and he's retired, but you know.
The movement to claim Traveller should only be ruled one way is an artifact of fans on the TML of the 1990s, not a mandate from GDW, DGP, or GURPS. We split mainly into Classic versus TNE and glared at each other, porting the term "canon" to Traveller and quoting what we thought of it as we went. Don McKinney was a moderating voice, saying that we all benefit when we admit that Traveller is much bigger than our comfort levels allow.
I'm in a constant tension of rebelling against it and joining it. Obviously, creative chaos is way more fun, and yet. Five years ago I was a lot more hardline about this is the way it's done and that's that. I blame everything except my own fascist leanings.