Because there’s sales text in the “educational” article.
You should use an XMPP server that respects your privacy. If you truly want privacy and don’t want to trust any server, we recommend setting up your own server. If this beyond your technical interests then we can setup a server for you and hand over the passwords. If we setup a server for you, then you’d pick the domain name and get complete control over who can use it.
Does the DOJ’s opinion, binding or not, actually matter with respect to this though? Impeachment is solely the prerogative of the House, and more broadly Congress. I don’t see how the DOJ as part of the executive branch can thus bind the House at all in this.
(Also worth noting that Impeachment technically isn’t a legal matter – it is a political process.)