You say that as if it's a bad thing?

In this context (massive data breach) - it is.

It's noncritical infrastructure by every definition and data was already stolen, waking up a PR guy to put something on their page is a waste of everyone's time

Ah yes, responding to the media during holidays will make the data crawl back to their servers!

If this were a private business, people would be piling on and calling for the executives to face a firing squad.

"People" here meaning in particular the types that frequent this very message board.

You can find a certain group of people to pile on for anything.

What does their comms team have to do with the massive data breach?

Answers. These guys can provide answers to the public.

Are these answers so critical they're needed on a holiday?

I don't know. There's nobody in the comms team to answer this question.

OK, so nothing to do with the massive data breach. But hey, you just really want to make a point about how upset you are that Europeans having decent work/life balance, so there's not point continuing to expose your little agenda.

Aviate, navigate, communicate. In that order.

ESA’s priority in this case is measuring the damage and then brokering a solution if needed. After that it should communicate to the public.

National Labs are closed over the holidays in the USA too.