It's an equally gigantic pain in the buttocks to be the only someone who can give out AWS credentials. Why does that have to be one person? Why isn't that role spread out across a team?
What you're describing is an organizational failure, even if that person were working 168 hours a week.
Sure, but organisations do fail. Saying "oh, that's just an organisational failure" doesn't stop it from happening. Putting people in an office together is designed to let them recover from failure faster. When a randomly selected group of people are absent at any given time, gridlock happens.
There are also better examples than "one employee with AWS credentials," and I feel we're bikeshedding on the specific bad example, rather than talking about the broader principle of coping with blockers when the team doesn't work the same hours.
What you're describing is an organizational failure, even if that person were working 168 hours a week.