Yeah, it's actually a sharp observation. Onboard, deployments can range from months to a full year in certain 'worst' cases. The sailors are locked inside the hull, so the small perks are a way to keep up morale and mitigate psychological effects. A real napkin is a tactical requirement for maintaining the 'Standard.' Like IRL:
This is one of the CSGs involved with the Iran situation atm. Before that, the same crew was in the Caribbean for Venezuela. The submariners have it the worst; they’ve barely seen the sun or felt the wind on their skin the whole time. The traditions and what Brody calls 'royal pageantry' are part of keeping up the Code of Conduct, which is definitely stricter. Hence Parker's need to inform his presence (the salute) wasn't for Garret; it was for the Hull Integrity of the ship. The Army guys are not used to the System providing 'comfort' as a control mechanism.
As for Garret's attitude, I guess it veers into fantasy, especially given the current environment, but together with Parker, they are the next generation. It's not too far-fetched that privately, between old oar-mates, they'd be cool about it. The brass definitely knows they have hundreds of horny people onboard. Perhaps these two even have their own shared history—what happens inside the rowing team stays in the rowing team... 😉