I am guessing the motivation for the air field on Guadalcanal was to picket the eastern approaches to Raubal, and New Guniea. USN carriers had made trouble thrice before, in February, March, and May, and there was a plan or expectation of another try at Milne Bay by the IJN. If the offensive it was to support has been canceled, then there must be other reasons for its establsihment.hisashi wrote:...
Operation FS was cancelled in 11 Jul 1942 seeing the fail in Midway, following a proposal of cancellation from navy general staff to army general staff dated 7 Jul. ...... On 1 Jun RAdm Yamada, 25AS CO, reported to 11th air fleet (a combined unit of ground-based/seaplane air groups) to propose the construction of airfield at Guadalcanal. They passed on the proposal to the combined fleet just after the defeat in Midway, not knowing the defeat yet. The combined fleet confirmed that no other airfield seems available between Rabaul and Guadalcanal by an additional inquiry to 25AS.
On 19 Jun the combined fleet directed 11th air fleet to prepare for Guadalcanal airfield. The first construction units, earmarked by the combined fleet, arrived there on 6 Jul. ....
There is also the question of the perception of practicality between Op FS & RE. My guesses as why Op RE was still thought practical & FS not, may be wrong.