>> Preserving data for a judicial hold does not give them leeway to use that data for other purposes

Does not give them permission. What if LEO asks for the data? Should they hand it over just because they have it? Remember, this happens all the time with metadata from other companies (phone carriers for example). Having the data means it's possible to use it for other purposes as opposed to not possible. There is always pressure to do so both from within and outside a company.