That's a matter for a court, or a court-appointed expert, to decide. You don't get to opt-out of discovery procedures by intuiting that the other party simply wouldn't be interested in what you have to say.
(This raises all kinds of legitimate corporate IP concerns, which the courts have extensive experience handling.)
So, really, unless the legal hold on Google is a blanket, encompassing order to preserve all internal comms, I find it difficult to be objectively certain they are at fault here.
They're not asking a court to impose onerous or abnormal preservation mechanisms, as evidenced by no other company of Google's size or scope deleting all messages every 24 hours.
Even the wording of the accusation does not even imply a policy:
> Like Mr. Pichai, other key Google employees, including those in leadership roles, routinely opted to move from history-on rooms to history-off Chats to hold sensitive conversations, even though they knew they were subject to legal holds
Routinely opted is not a policy. A policy is formal, not an option you routinely take.
I'll wager even the best lawyers will be hard-pressed to prove this routine is primarily to render discovery impossible. In fact, on face value alone it will be hard to objectively prove any purpose to this, unless more info/evidence/data/witnesses come up.
The text that follows my quote
> they did so even when discussing topics they knew were covered by the litigation holds in order to avoid leaving a record that could be produced in litigation.
makes assumptions that you can only speculate on, not prove. Sure, they were discussing topics covered by the litigation and then pivoted to private chat within nine seconds. Does it follow that the part of the conversation they moved off-record (and hence we are not privy to) is also definitely covered by litigation and could affect the outcome of the trial? Not necessarily (although likely, alas courts don't settle for likely).