Depends on how you configure it. Normal operation starts charging when it detects a sufficiently high input voltage. So charging voltage from the phoenix would trigger the Orion.

There's a number of switched options using the LH terminals. Normally they're bridged, which is always on. These can give the control you need. If you use a switched feed from the ignition switch on the starboard engine to the H terminal and remove the bridge wire, you'll be where you want. But it won't stop the Orion if you run the engine while shore power is on.

Which raises the question, does it matter if the Orion is on when shore power charging is on? The house bank and outputs from the chargers are voltage driven. So no harm will be done.

There's a full description of the settings in the pdf manual. https://www.victronenergy.com/dc-dc-converters/orion-tr-smart#manuals

Also download the engine on detection pdf, which is downloadable from the datasheet option.