The appropriate response to Client is "Great, but it will cost $Z in Friday fees"
In my opinion, only the last one may be justified.
And my own darn fault for using platform Y from team X that would release a security update on a Friday. Yes, fix it. But if this isn't a one-off, get off of platform Y.
Are you suggesting delaying security updates because it's Friday? I mean, you can update only on Monday if you so wish, you're unprotected either way.
If platform Y regularly releases security updates on Friday, that's poor management by X and I would reconsider using platform Y. 0-day issues of high severity should be the exception.
Timezones can make it so. It's not necessarily their fault.
[Client, Friday 4PM] "We are having a big sale this weekend we told nobody about. Could you quickly deploy a fix where all the product's prices are red and bold? That shouldn't take you long, right?"
[Project manager, Friday 4:45PM] "Hey team, X just released an important security fix for Y platform. I need you to deploy it right now or the client could get hacked."