Oh, I have no doubt that SE really did plan to treat all 1.0 players as 'Warriors of Light' originally, because that's all that was ever stated on the subject - Yoshi just said that 'all 1.0 players would get a special storyline', and didn't clarify or elaborate on it - however due a bug that could not be fixed in time, the game couldn't differentiate between 1.0 players from new players.
During Phase 3 of the Beta when this bug was first apparent, I didn't get the Legacy opening and no extra dialogue from npcs who should have remembered my character, however, one npc who ironically stated they did recall my character yet shouldn't have because he had never met her at all in the first place was Rahbaun during the level 15 main story 'envoy' quest (possibly because my character was a GLA at the time she spoke to him in that quest). This was fixed in Phase 4 however, where he didn't have the extra dialogue, so it basically showed that it was a bug after all that SE ultimately couldn't fix in time.
So SE probably just settled on the Lunar Transmitter battle as the cutoff point for Legacy opening requirements and retconned it accordingly. It's unfortunate, but it's not too big a deal.
In any event, as has been already stated, it's irrelevant anyway as
by the end all players are regarded as Warriors of Life, regardless of whether they destroyed the Lunar Transmitter in 1.0 or not, or are adventurers newly taken to the 'path' - all are referred to in the ending of the main scenario by both Hydaelyn and the leaders of the Grand Companies as a 'Warrior of Light reborn', and as their 'Champion'.