I guess we are splitting hairs over semantics.
Is an interim title shot a title shot? Technically but not really, since all it does is guarantee you a shot at the real title, but it has the words "title" in it so yeah I suppose it is one. But it wasn't a rematch like with Suga, he still had to win another fight to get that.
I just don't like the lack of context in any of the arguments made - he didn't lose a title fight like Suga i.e. got clearly beaten, he got DQ'd in a fight he had basically already won. That's kind of important when the visual narrative is one guy winning a fight and then landing an illegal blow where the other guy puts on an over-the-top acting job to guarantee a DQ. Then he lost the closest type of split-decision possible to the same guy after putting on one of the best BW fights of all-time against Sandhagen.
You say he "couldn't beat Sean on his best day" - who said that was his best day? And if we use perceptive reality as "who won" not just the three guys the UFC essentially pays to be there by paying off athletic commissions the majority of everyone believes Yan won - fans, media, fighters.
Beating Faber made him 6-0 and the UFC was in a shit-spot with Cejudo vacating the title, Moraes shit the bed and they gave him a bounce-back fight against Aldo dropping down and it was a coin-flip that could've gone either way. They promised Faber a title fight if he beat Yan, so it's likely Yan got the same promise with a win.
The UFC was short on name-value contenders with TJ out with EPO doping, Cruz getting smoked by Cejudo, Cejduo retiring, and Moraes shitting the bed versus Cejduo. At that time who was left to fight for the title? The rankings were:
Moraes > "beat Aldo" in fight 50% of media and 60% of fans thought he lost (would go on a 7 fight losing streak after this, hasn't "won" since, so if judges went a different way would be a 9 fight losing streak)
Sterling > booked to fight Sandhagen
Yan > not booked
Sandhagen > booked to fight Sterling
Assucao > booked to fight Garbrandt
Aldo > "lost to Moraes"
Munhoz > lost to Aljjo, booked against Edgar
Rivera > coming off a 2-loss streak to Aljo/Yan
Garbrandt > coming off a 3-loss streak of getting KO'd, was booked against Assuncao the month before
Font > 3-2 in his last 5, coming off 2 wins by decision over Simon/Pettis
Timing/circumstance/what have you done lately/how have you done it/name-value - these things all come into play. Based on the landscape it looks like Yan was putting on incredibly exciting fights, winning all of them, willing to fight anyone anywhere, and the division was log-jammed with a bunch of guys at the top already booked or coming off of loses/mixed performances. Dana White even tweeted out after Cejudo retired that the Vacant title fight would be "Petr Yan vs. Somebody" so that's just the way he cards fell.
The 4-4 since challenging for the title is pretty void of context - those losses:
Aljo 1 - DQ in a fight he had basically won; a loss on paper but everyone's memory of that fight is Yan breaking Aljo then committing the foul which Aljo oversold unnecessarily to get a DQ.
Aljo 2 - Split-decision in a fight he could've easily won, about a coin-flip a fight as can be.
Suga - Split-decision loss in a fight the majority of fans/media/fighters think he won.
Merab - Came in with an injury, got another injury immediately, and got ran over by one of the best of all-time to do it.
His losses are to the last 3 champions and he arguably won 2 of them, he never got finished and the only domination was Merab who does that to everybody. That was a fight he shouldn't have taken since he was so injured and he's even admitted as such, but it's his fault for taking it so he needs to just eat the L. Yan's record is one of those ones where if you don't watch the fights and just look at the "official record" it completely negates actual truth.
And I don't see why you hate the Russian fighters specifically, they are no different than any other nationality - most fighters are entitled, have excuses when they lose, and are hypocrites.