Yep, it's pretty clear that unlimited is going to have limits (250 TB is a lot of data, that'd be $1500 a month in Backblaze). However, Google should have been required to be up front about their definition of unlimited (eg: up to 10 TB), rather than leaving it as a nebulous ToS term they can arbitrarily decide upon in the future.

This is actually a good use case for something like AWS Deep Glacier or Azure Archive Storage: data that needs to be saved and accessed infrequently if at all. It'd be around $250/mo, but as a business expense for a professional journalist that seems reasonable. Amazon or Microsoft could of course turf those services in the future, but considering the number of large companies that use them for long-term archiving I would expect that there would be a lot of notice before taking that step.