Well it was a bit of a joke but… Yeah he senses him and hunts him down like he did before because he knows Obi-wan is no longer around to train Luke.

Unlike in the films he keeps on saying “Obi-wan has taught you well” even though he killed obi-wan after a few days. Obi-wan as a ghost only really provided guidance for Luke not really any proper training or at the very least it was quite minimal.

He was not meant to die in star wars that is why Yoda was created so Luke had a mentor again. But Vader was meant to hunt down and murder the Jedi was he not?

It’s either that or propel Yoda into the plot somehow other than just die peacefully. So that Hero death was a bit of a weak point.

If anything it was a missed opportunity Vader and Yoda in a scene together whatever the outcome it would have been really interesting.

I could actually imagine more Yoda and the Emperor with some cool dialogue and perhaps Vader Subdues in the background perhaps the Emperor sends in his muscle on Yoda or something like that.