It's probably some malicious compliance on their part. They are probably storing those timestamps, as, well, UNIX timestamps. So it's exactly what they provide.

Meh. In any case involving data/tech I suspect there are people involved who can handle much more sophisticated formats/conversions than this. I may disagree with the government’s stance on privacy, bit they’re not stupid or tech-illiterate.

I regularly help my lawyer friend parse the DVDs she gets from police with the evidence from her case and it's a nightmare collection of proprietary ancient standards for old versions of Windows. They also still use fax machines for everything.

The only place you'd find technical talent is in the federal police or a few guys higher up in the major urban police forensics labs.

Sure, but my point is that any agency or group that is going to subpoena Signal definitely has someone on their team who understands what a UNIX timestamp is. Think about it: If a service actually does comply with one of these subpoenas, they probably had over a trove of JSON files that need to be parsed or searched.