First, in this TL there is no Aleutians attack. In all the books i have read i have never came across any statements that Nimitz intended to do what it is said above, especially the bit about evacuating Midway. He wanted to fight at Midway because he saw the opportunity for ambush, plain and simple. Probably if he would actually evacuate Midway instead of fighting with his absolutely intact (in this TL) four carriers vs. six japanese will cost him his seat the moment King finds out. His instruction in regards to Midway were primarily not to lose the carriers, and quote "if things got rough, to let Midway fall" to conserve the carriers (if they sustained too many losses/damage), which btw shows his evaluation of Midway garrison's ability to repel the japanese invasion. On the other hand, he was also confident that Midway could have been recaptured later if this was to happen. But i do not think it would have been so simple, the USN in 1942 was not the one of 1944, Tarawa would be nothing compared to what an american invasion of Midway would have been. I know what you are going to say, this proves that the JAPANESE coudn't have taken Midway, becasue of the littany of arguments about doctrine and support and all that that imo are largely mistaken, as i pointed on several occassions. 1942 is not 1944! The main thing is the japanese do not fight like the americans, whether invading or defending they usually fight to the last. Midway could possibly be another Wake for the americans, but if they try to take it back, it would be a double or triple Tarawa for them.
But anyway, the whole point of Midway from the japanese side was to destroy the US fleet, not taking the island. If they would somehow win the naval battle (while suffering heavy losses themselves), they probably give up invading Midway, maybe just bombard it with Kurita's cruisers but not try the invasion.
On another note, one other way to actually butterfly away the Coral Sea and perhaps the Aleutians operation too is to have Kido Butai discover Somerville on the morning of 5th of April. Over one hundred japanese carrier aircraft will gun for him, most of his force will share Cornwall and Dorsetshire's fate, it will be an overwhelming victory for Kido Butai, but they would still lose two or 3 dozen aircraft to all causes, so even if they want to sent Cardiv5 to the Coral Sea they couldn't because they would need time to replenish losses.