1- Whitebeard's reflexes were slower than usual, evidenced by the fact that anyone who knew him said he wouldn't have gotten stabbed by Squardo under normal circumstances
And by the time WB got around to fighting Akainu, he could counter several of Akainu's attacks without trouble detecting them. Unless you're saying Squardo's stab was faster than Akainu's and Aokiji's attacks, WB's drop in reflexes at that moment were a temporary lapse in his abilities. Meaning, that's a moot point.
2- Whitebeard had problems to control his haki(at least his conqueror) due to health problems evidenced by when he failed to knock out the guardians that were about to execute Ace
Caused by a heart attack that struck at that moment. WB's Haki affected Akainu, something Marco's and Vista's couldn't do, also renders this into a moot point.
3- The stab injury Whitebeard got from Squardo was severe enough that even an endurance beast like Luffy couldn't believe he could still fight after that
And Luffy is aware of anything WB can do? What's Luffy's frame of reference? For one, Luffy was COMPLETELY out of his element in that war. Almost everyone there who was worth noting were leagues above Luffy, so of course feats by them appear to be otherworldly and amazing to Luffy. Note that Garp, Sengoku, Marco, Akainu, Aokiji, etc. made no note of how special it was WB could still fight after that blow because they're on a level where they know shit like that is laughable. Literally. WB laughed at the notion of such a blow doing anything to stop him. So again, moot point.
4- On top of those handicaps, Whitebeard received much more injuries during the war, to the point of being close to a half dead state before even facing Akainu
I never denied this.
SSelf says that Akainu would have lost to Whitebeard at the moment he was jumped during their second clash. This would mean Akainu lacks the ability to do something Teach and his cronies did, which was kill Whitebeard. This would mean Akainu is inferior to Teach and company. Akainu clashed with dozens of pirates and the WB commanders, and left without significant or further injury, indicating that Akainu was at least equal to them if not superior. If Akainu was inferior to Teach, as the previous premise dictates, then this would also mean the WB company that clashed with him is also inferior to Teach and company. Which I don't agree with.
5- I don't even get the analogy between the scenes you presented, but even if we take into consideration the intial shot Whitebeard gave to Akainu, Whitebeard was still in a considerably worse state(a minor-to moderate injury compared to someone half dead isn't even comparable) than Akainu after Akainu retaliated, yet even on top of these multiple handicaps, Whitebeard still slightly dodged Akainu's assault and KO'd him with a quake for a considerable moment of time, but ignored him because he had other things to do.
People say WB whooped Akainu's ass but that's only because Akainu was jumped. We've seen that when a character is jumped and caught off-guard, even people weaker than them can deal great damage. Caesar incapacitated Luffy via jumping him. Yeti Cool Bros. incapacitated Zoro via jumping him. Hell, the entire premise of Law's attack pattern against Doffy was misleading him in order to jump him with surprise attacks because he knew was too weak to hit him head on.
The point is, jumping someone can yield results that wouldn't be accomplished by a head-on assault. And the same can be applied to Whitebeard: Just because WB was able to whoop Akainu when he jumped him doesn't mean that the same results would have happened if it was a head-on assault from either men.
If even on top of all those advantages, the best Akainu could achieve was being a little weaker, he'd have been eaten alive by start of marineford Whitebeard, let alone his prime self
Considering that Aokiji, Akainu's more or less equal, was not, I doubt it.