Star Platinum is pretty damn precise and will most likely sense the vibrations before the arrival of the initial attack appears before his observation.

So he'd likely avoid the initial attacks, pull out a time stop, and pummel Vlad for a bit, if Vlad lives through that he realizes he's in a tough spot and puts a stake through Jotaro's heart

Note that I don't think that Vlad can see SP without Servant Physiology

Well if the stats are equialized, you must take into consideration that he now has Star Platinum's MFTL+ speeds, and unlike a stand, he must obey the laws of natural physics, and would most definitely blow up the earth with one single attack lol, unless ofc your rule is also to make it so the force of speed/acceleration is somehow suppressed despite having said amount of speed.

Similar to how most MFTL stands don't destroy the planet (since they don't abide by the laws of physics).

"and unlike a stand, he must obey the laws of natural physics, and would most definitely blow up the earth with one single attack lol"

When has this ever been an issue in any anime? your point is to apply real world physics to a verse that doesn't operate under them

Oh boy here we go. I am completely aware of the fact that things such as that don't really apply to fiction, but it still has complete 100% relevancy. You can simply fix things by making a new rule that says "He also follows under the logic of a stand and will not blow up the earth with his MFTL+ attacks".

That's the assumption, does either have a planetary feat off speed? no, so thats not a factor here

A jump from slightly FTL (being at island level) to MFTL+ speeds would definitely put him at a planetary+ category, so that error is kind of on you.

No it's not, and typically equalization scales down