[t0mas88]

The "requested" part sounds like it's not mandatory, otherwise they would have used something like "you're not allowed to..." or similar language.

[namibj]

Sounds like a notice that disclosure could result in outcomes that make the discloser liable of (the crime? of) interfering-with-an-investigation.

And thus to avoid that risk, to think twice before disclosing. Disclosure would only be punished if the specific circumstances actually result in legally-considered-(unlawful-)interference.

[walletdrainer]

There needs to be specific intent to obstruct, merely sharing the subpoena does not demonstrate this.

“Hey, we got this subpoena. You better quickly wipe all your drives” probably would.

[AlienRobot]

The "supposed" part as well.