Cooley in particular wouldn't necessarily delay his RFA status if he returned for his sophomore year and signed his ELC in April 2024. The only downside would be that he'd be a 10.2(c) RFA after the ELC (no arb rights and wouldn't be offer sheet eligible), so he would have a little less negotiation leverage.
I wouldn't be surprised if Cooley opted for another shot at WJC Gold + National Title after getting close last season. Rushing in to sign with a club that's not expected to be competitive this year might not be as appealing.
It would be ill advised for him to go back to school. He would be losing out on a million bucks and he is screwed if he was to ever get hurt playing NCAA.
Also, nobody in the NHL is able to "set up their lives". Anyone could get traded at any time.
That feels more like an NFL mentality where an injury could completely derail somebody's career.
I'm trying to think of a drafted NCAA prospect who had a detrimental injury when they had the option of turning pro. Just recently Owen Power, Kent Johnson, Matt Beniers, and Luke Hughes went back for their sophomore years at Michigan.
On the flip side, Alex Turcotte left Wisconsin after his freshman year and has had a litany of injuries since turning pro. Unfortunately due to the ELC slide rule, Turcotte still has one more year remaining on his ELC. Meanwhile his NTDP teammates like Matt Boldy, Cole Caufield, and Cam York are going to cash in this summer (Boldy already got his extension). Boldy/Caufield/York went back for their sophomore years as well.
Arguably Turcotte cost himself money by turning pro early.