It's canonically valid, on pure technicality. But, it's got terrible flow in terms of writing and plot progression.
All that said, I can't help but feel that Kubo PURPOSEFULLY made Tsukishima as a way out for him, in the rare case that Shounen Jump decided to axe Bleach and he had a very short chapter count before the manga ended. It's basically a get out of a jail card for him, that he probably hoped to never use--but was there if he absolutely needed to.
And since the manga is to supposedly end within the span of the next five chapters, Tsukishima's ability allows him to effectively "undo" the hole he is in as well as the hammer that's coming down from Jump.
This way, he can bypass the chapter count he would otherwise need to normally "fix" Ichigo's powers and simultaneously leverage Orihime's broken as fuck powers, to "fix" Ichigo's bankai and restore Zangetsu.
>Ywach stole White & Quincy powers
>Tsukishima negated, via a retroactive continuity (which generally is something to be shitted on, but by powers that be and within canonical validity, is now pure genius), what Ywach did
>Coupled by Orihime's rejection of events based on the now modified past to present continuity
>we have a situation where Ichigo DID fight Ywach, get his shit kicked in, and have his bankai broken
>Only to have these events rejected completely, creating a new future for Ichigo where he escapes outside of the reach of the Almighty
This way, Ichigo can now face Ywach again, and his almighty powers will have no effect. Then it will simply be a battle of who's offensively superior.
This is pretty much level 9 Kubo now. It's logical, accurate, valid, and absofuckinglutely magnificent--while simultaneously being utterly retarded, as it completely disregards good writing principles.
Kubo is without a doubt a fucking hack, but within all that, he has his moments of pure genius and this moment right now, probably crowns as that. Can't think of any mangaka that can top this.