Would it matter if the Bidens really did have something corrupt going on in Ukraine?

That Suleimani was indeed a bad guy whose job was to plan terrorist attacks and devastation of civilian targets, among other, and that he doubtless did have enterprises at various phases of the planning stage do not add up to legal justification (no imminent threat) for acting without prior consultation with at least the Gang of Eight, not do they make this a lawful targeted killing rather than an illegal assassination.

Nor, of course, do those facts prevent this attack from being a wildly reckless and evil gamble (consider how may people would have died, lots of them Americans but mostly others and a lot of them noncombatants, had this gone as wrong as it might have), a wag the dog blow against impeachment, a campaign stunt and a thumb in the eye of Obama and the Democrats

So, if there really was dirt to be found on the Bidens, would that convert his impeachable subordination of foreign policy to the need of his reelection campaign to "dirty up" Joe Biden to a perfectly lawful hunt for proof of corruption?

No.

The crime boss in the White House is as far from being an Eliot Ness crime fighter as Al Capone, and is just as disturbed at the thought of corruption among government officials.

That is, not at all.

Unless pursuing it can serve his own interests, likely criminal themselves, in some way.