Taking a step back, considering that this is a service that doesn't have any SLA, then the service provider is at liberty to do what they want when it's most convenient to them.

And from their point of view doing changes when they have their full quotient of techies around to fix any fallout is probably more sensible than doing it out of hours and then have an extended period of time of sub-optimal performance due to bugs not being noticed, reported and fixed? Also if the site is "busy" from a customer point of view then any issues are more likely to be reported promptly and resolved?