I think that Billinjah's point is absolutely the key to it - if you take the starting point to be LH (rightfully) alongside KR, then he didn't gain any advantage relative to that starting point, in fact a disadvantage.
Starting point??? He was trying to overtake round the outside and it did not work, therefore you would expect him to end up well behind Kimi since he left the track.
You don't seem to want to look at the film. You say 'it did not work' but if you were to look at the film, you would see that LH was partially alongside KR and had the inside line for the second part of the chicane. Had KR given him room, as he should have done, they would probably have exited the chicane neck and neck. But KR went for the apex and if LH had held his ground, his right front wheel would have hit KR amidships. There would then have been an issue over who was to blame, but as LH was alongside, KR was pushing his luck in heading for the apex and forcing LH off the track. If you'd been watching F1 as long as I have, you'd have seen many occasions when manoeuvres like LH's have worked, provided they weren't forced off the track.
Billinjah is right to say that there is a strong case for saying that the point at which KR forced LH off the track should be the starting point against which to measure whether LH gained an advantage from leaving the track.
If you were willing to look at the film, I can't believe you would make these points.