I read it a completely opposite way, which is part of what makes the scene so beautiful. On my first watch, I was totally taken in by what seems to be clear evocations of Hoth with the Snowtroopers and Probe droid. Given that, I originally took the scene as being ESB time period. Specifically, after Luke makes his fateful decision to die before joining Vader, which prompts that beautiful series of self reflections for Vader as he realizes he has become so monstrous that even his own son would rather die than join with him. It leads to one of the best scenes in SW where Vader steps away from the glass on his Star Destroyer, than glances back out into space longingly before finally turning around and walking pensively down the bridge. That’s the moment Anakin was reawakened in him. And from that point on the armor of Vader weakens as Anakin starts to emerge.

Given how it seemed Filoni and crew were trying to entrench us in that ESB time period with Hoth-vibes, my original thought is this scene followed that self-reflection on the bridge after Luke fell. Initiated by Luke’s refusal, Anakin starts to realize how much he has fallen, he starts to remember what he used to be versus what he has become. And suddenly the guilt of, as he thinks, killing Ahsoka on Malachor, comes pouring back and he goes to visit this site of where he thought a lot of his old life came literally crashing down, Rex, Ahsoka, and half the 501st. He decides to finally go investigate the site he assumed Ahsoka had died at originally, as he starts to feel his own self recriminations, only to find some of the most poignant memories of his old life he could. The ship he last put Ahsoka and Rex in command of and where he last saw them both as Anakin, the graves of the 501st, half of ‘em with their helmets painted as Ahsoka, and finally the lightsaber of his padawan that he had maintained and altered himself. It reminds him he once had a heart.

And seeing Ahsoka’s owl, representative at least to the audience of the Daughter and Ahsoka, the Daughter who sacrificed her life force for Ahsoka to live (reminds us of Vader saving Luke) shows him he isn’t stuck where he is, there is hope beyond hope of a new life after darkness and death. For him, he likely doesn’t realize the owl represents the Daughter, but he saw it with Ahsoka on Malachor. It watched him limp out of there. And here it is, all these years later, after his own son rejected him, life flying above the wreckage of his past, almost like Ahsoka encouraging him once more. And this time, with the ice broken by Luke, her loyalty to him actually helps cement his return to the light. That’s why he didn’t react angrily or in disgust when he found the lightsaber or looked up at the owl. He was pensive, gentle, even, with the hilt, and deep in thoughts of times past, before the owl hints to him, maybe there is life after losing everything.

Given Filoni’s insistence on the fairy-tale nature of SW and his consistent lauding of a happy ending because of that, while also remembering he wanted to strictly adhere to the tones of RotS and his awareness it could not end too hopefully because it was meant to be the darkest time in the saga, the most Filoni-esque ending for TCW would be a Vader scene with the smallest glimmer of hope wrapped inside.

Of course, this was reading much too into the clearly Hoth-reminiscent setting as a hint at where we are in the time period. He appears to be more in his ANH garb, which seems to put to bed post-ESB theorizing. Still, I think it was certainly after he thought he killed Ahsoka. Elsewise I think he would have brought that lightsaber to their foretold meeting on Malachor to gloat and antagonize her with. And I still can’t help but read his seeming reverence for the blade as a moment of self reflection. So even if it’s post-Malachor, ANH era, I have a hard time seeing him as angry in this scene, which is what you would expect Vader to react with to being confronted with these relics of the past (which is exactly his reaction to seeing Ahsoka on Malachor, hatred, as she represented everything he lost, per Filoni’s own words), whereas Anakin would react with this sort of reverential longing and self reflection.

I will say, at the point the stormtroopers had become the bulk of the Empire’s forces it already would have been years after RotS, which would have been years after Anakin had been completely broken already. While I think you can read it as a moment of self-reflection in a negative sense, more in a it was agonizing for Vader to find it and helped bury Anakin even further, but Anakin Skywalker broke long before finding that saber.