Rich Hammond of the Orange County Register reported Galette took a physical, which came back clean, but he didn't end up receiving a formal workout with the organization.
"It just didn't work out for reasons that we will keep inside," McVay said.
The 30-year-old Haiti native racked up 22 sacks between the 2013 and 2014 seasons for the New Orleans Saints but proceeded to miss the next two years because of Achilles tears.
Galette returned to play for the Washington Redskins last season but struggled to match his pre-injury form. He recorded 20 combined tackles and three sacks in 16 games.
In May, Herbie Teope of NFL.com noted the veteran pass-rusher wrote on Instagram he didn't join a new team during the initial wave of free agency because he was thinking about ending his career.
"The real reason I haven't signed is because I've contemplated retiring," Galette wrote.
His focus has seemingly shifted back to playing football. Galette made a Twitter post early Wednesday about his intention to make a major impact once signed:
Although things didn't work out with the Rams, he could provide valuable depth for the Seahawks, especially with projected starting edge-rusher Dion Jordan questionable for Week 1 because of a shin injury.