That explanation doesn’t really fly for me, since it takes a spectacular amount of obtuseness for Vader to not at least suspect that the Force-sensitive teenager who blew up the Death Star named Skywalker is his kid. Acting dumb just makes him look like a buffoon in front of the Emperor. Besides, since Vader is openly calling this kid ‘Skywalker’ from the beginning in an obsessive hunt, there’s no reason that the Emperor wouldn’t know his reasons for searching. Hell, I’m sure the paperwork on the probe droid operation would have been labeled ‘The Search for Skywalker - Probable Child of the Famous Jedi of the Same Name’.
Also, the idea that Vader would have some ill-will towards Palpatine for calling Padme’s death a few hours early seems like a stretch. It’s technically true that Anakin and his anger killed her, even if the details aren’t exactly as it seemed in ROTS. The fact is that Padme eventually died at Anakin’s hand and a child exists, something that isn’t impossible so Vader’s astonishment, feigned or not, is silly.
Well said NeverarGreat, you worded the issue and highlighted the cause for confusion a lot better than I did. 😃