Always a sad moment when a search is called off, but I never recall a search I was involved in being called off without us thinking that everything possilble had been done and that there was no other option.
In this case it a relatively small area (4800 sq. miles has been quoted), presumably based on an accurate LKP, was searched from early Friday to early Sunday. Not sure a longer search would be justified.
What is worrying is the failure to investigate the upturned hull more thoroughly.