Is using a shielded industrial cable a bad practice when used as an outdoors AC mains cable?
It depends on your jurisdiction, but it is unlikely that that particular cable meets all of the code requirements for mains wiring.

I would recommend using an isolation transformer for the mains connection, and use a 1A fuse in series with this cable.

There's nothing wrong with using shielded cable per se &mdash; it probably brings some benefit in radio applications.