I'm probably missing something, but the 50-star rules seem a bit inaccurate inherently.
"Beat the game as fast as possible, with the following restrictions: Mips Clip, LBLJ and SBLJ are banned. That is, you must go through the 8, 30 and 50 star doors by unlocking them. [...]"
The "that is" interpretation of the previous sentence seems inaccurate as you could get through the 50 star door with a regular BLJ (not banned obv because you need it to get up the infinite staircase).
Wording could be easily revived to, "Beat the game as fast as possible without clipping through any star doors." The 70 star door opens for you when you only have 50 stars, so you're not clipping through it. I am pretty sure that this wording allows for the exact same runs, without the terminology mistake.
Aaaand if no one cares, that's fine too lol.