Realistically, though, it is hard to see King and Nimitz deciding to do WATCHTOWER if they just got kicked at Midway.
Much more likely that they continue the buildup on the key islands in the SE Pacific, and keep the surviving carriers to at least pose a threat of a fleet in being. I do think you may be onto something with both VICTOROUS and FORMIDABLE being sent out as temporary reinforcement.
Why stop the operation. Kido Butai is not magic, it cannot be in two places at once and will have had massive losses in the air groups - the IJN always did and US traffic analysis had a good fix on major units during this period. The carrier force for Watchtower is a distant cover force and not doing this now means the IJN can create a large airbase you will have to reduce later. Its not a given either way but the reasons for launching the op don't change. Nor does the aggressive use of the available USN forces. They have been doing this since day 1 of the pacific war. What has changed is the availability of 1st Marines to use aggressively. KB would counter raid but its a raid. Every time the force deploys its risks being hit by a sub, and burns fuel.