Legislation to protect e-mail mailboxes as the same way we do with official postal (snail-)mail services in most countries needs to be handled very carefully, because otherwise we'll end up protecting spammers - the very opposite of the people we want to protect.
I see this story as Google's equivalent of when Valve would ban people from Steam for crude comments they made on the Steam forums, which I understand meant they forfeited their entire game library - or Amazon banning people for reviews.
If there is going to be any law or legislation - it should be to require service companies like Google, Valve and Amazon to treat the customer's "online personality account" (i.e. forum account, "community" account, etc) separately from their "value" account (i.e. whatever that which has _value_, be it their Steam library, their GMail mailbox, etc) - or at the very least, companies must be required to export 100% of the data in an account and providing that to the customer/user in the event they shut down an account (with reasonable constraints, such as the account having existed for at least 3 months and having been in good-standing until this specific incident, etc).
And under no circumstances should anyone lose their software copyright licenses for violating a community ToS - feel free to ban them from the forums, et cetera, but being banned from the Steam forums must not mean they lose the right to play the copy of Half-Life 2 that they paid for.