The political realities of timezones is _exactly why_ you should be storing the timezone name if the user is scheduling it for an event in their local timezone. If a user is expecting an event to happen at 6pm in their local timezone, and political reasons cause that timezone's offset to change (ie. daylight savings), it will still happen at the correct local time for that user.
Storing UTC offsets means that any future political changes will result in the wrong local times for users.
I did notice that the owner of a large mining pool was receiving error notifications from Mt. Gox. This mining pool has tampered with mined blocks to include religious messages, so they'd definitely be in a position to do transaction malleability attacks to provide Gox with plausible deniability.