It explains both. Blocking archiving will save a bunch of bandwidth as well as not having to scale up the servers for the load of dealing with the archiving.
But it doesn't excuse much. Capt. Obvious says, "it's temporary, it could have been anticipated, 'protecting' their datacenters from the load in exactly this way will almost certainly be interpreted as ill will, there are options not being taken such as throttling or even voluntarily sending it all to archive.org"