Tell that to the crews of the Pensacola, New Orleans and Minneapolis.
Yorktown had 3 of her 8 boilers knocked out when she left for Midway. While it maybe possible to get the boiler feed pipe to be fixed en route to or at Pearl and get her boilers working. But you are ignoring the two torpedo holes in her bow. Which are allowing water into the ship as it goes forward. Patches for the torpedo holes are not an easy or quick thing to fix. Also, if the Avgas system leaks are fixed then she can fuel her aircraft. Which is vital for her operations. As a frontline carrier, otherwise if not. Then she would be a liability . Also, Nimitz knew he was out numbered in flat tops and I have no doubt that if Lexington survives. He would do everything possible to have her ready for Midway. But as I keep telling you, those torpedo hits cannot be temporarily fixed to a battle worthy condition in 2-3 days.
Actually a Yorktown-Class can be loaded to 96 aircraft. Also Station Hypo informed Nimitz that the Japanese will show up on 4 June. The wildcard was whether Zuikaku would show up as well. As explained by Jon Parshall in his video with Drachinifel last year. Also, neither Shattered Sword, Craig L Symonds Book, Wikipedia, Jon Parshall, the US Naval Institute or anyone else suggested that just prior to 4 June 1942 the base on Midway was struggling to service and prepare 126 Navy, Marine Corps and Army Air Force aircraft. It would be a tight squeeze but it’s something that could be done. Finally you said it yourself that Nimitz knew he was outnumbered. If Lexington was out of action. Her Air Group was still of use and he would not allow it to remain in Hawaii during the Battle. Either they would be flying off a carrier or flying off of Midway.
We are debating all these issues in a vacuum. We don't know what condition Lexington's hull was in. Your assumptions are based on what happened to other carriers hit by torpedoes. When Saratoga was torpedoed on January 11, 42 she had 3 boiler rooms flooded and was capable of only 16 kts. The strategic situation at the moment didn't indicate the Japanese were heading for the Hawaiian area so, they took the time to land her 8" guns, and send her to the West Coast for proper repairs, and upgrades. My assumption is based on Lexington being able to maintain 25 kts speed and continue air ops.
When she reached Pearl, an assessment would've been made to see what they could do with her. The strategic situation in late May was very different than when Saratoga was torpedoed. The Japanese were coming with 4 possible 5 fleet carriers, with several light carriers in the operation as well. Intelligence said the Japanese would attack Midway on June 4th, but until it happens you don't know it will happen. That's why Nimitz wanted his carriers in place several days before the 4th. If you can use a damaged carrier, you're more likely to take the risk in an emergency then in a less stressful situation. Rushing Yorktown's repairs was a risk, but Nimitz made the call and history Prasses him for it.
If Lexington couldn't use half her fuel tanks it might slow her air ops, but she would still generate enough sorties for a 2-day battle, which should be enough. She'd be operating with a short air group since with the scramble for carrier aircraft her loses at Corral Sea couldn't be made good. The carriers that went to Midway had 233 aircraft embarked, and we don't know how many Lexington would be bringing back. There weren't that many more carrier aircraft with crews waiting around.
To my knowledge no Yorktown Class ever went into battle with 96 planes in her air group. Air ops would be a nightmare, especially later in the war when some aircraft types were bigger than the ones being used in 1941/42. Nimitz wouldn't overload his carriers like that, it would only make them less efficient, and he needed them to be at their best at what might be the most critical battle of the war. If Midway was overloaded with 126 aircraft how many more do you think it could take?