1. Privacy issues. If a game goes offline and people still have code in the game to show leaderboards then hackers might be able to get people's data.
Yeah, as you wrote yourself, this is pure BS.
Even if that was somehow the idea of the initiative (it is not), if hackers can gain access to people's data via leaderboard, they can do so regardless of who hosts it. Or rather, whoever hosts it would be responsible - but that's not the dev/publisher anymore past end-of-life.
BUT: Nobody demands live data be kept around past end-of-life. I mean, if the dev/publisher wanted to go that extra mile, I doubt anyone would complain, but that is in no way part of the "reasonably playable after end-of-life" idea.
2. Which leads to liability issues. If the above happens, they dont want to get involved with lawyers and costs to cover something they said they cut the cord.
Very obviously, there cannot be liability of the original publisher/dev past delivery of the end-of-life "update" (in whatever way, shape or form).
One thing that will have to be determined further down the line in this, is what would be an acceptable state for that update/version. I'm sure this is where most actual legalese would come in.
There would also have to be some kind of authority to determine if that end-of-life update ticks all boxes it would need to.
Personally, I'd expect something as "low" as an offline mode, without any direct server code*. Maybe the odd goodwill dev/publisher will deliver server executables, but probably rare. But that's all speculation.
Either way, the main point is no liability past end-of-life (other than delivering a way to play, even if just offline).
*For pure online games such as MMOs, this would likely translate into the client running some kind of local-only server mocking actual server-replies/commands. This is a standard method for developers already in application testing, including games.
So don't let any fool tell you this would not be possible. It is very possible, and fairly easy to boot.
And the company has to go through the wringer defending themselves.
Oh no.
Poor company.
I hope they can use all the GaaS money to dry their tears. Maybe fire some people so the execs can remain overpaid, now that's a novel idea!
More seriously, though: Very likely, this entire process would need to take input from all parties to get a law that would exclude possibilities of "frivolous" lawsuits. I expect one major point will be the "no liability" I mentioned before.