Firstly, don't log and pirate only when you see a ship in Gallia. What I mean by this is that Gallia is very low on activity and if every time the few ships that do appear in Gallia they are pirated they will just not bother. Some of us are active in Gallia quite a bit, IDF, GMS and at the moment to a lesser extent EFL, so we wouldn't object to the interaction.
Tunicle and I also have Brigand Characters as well, so I am sure that we can help, even though we hardly log them.
I am also of the belief that Pirates are very 'protective' of their turf so any other Pirates would be frowned upon and shown the door. To this end I wouldn't expect Sirius Pirates being allowed to operate within Gallia unless under extreme circumstances. Trading would be fine but a Pirate Code of Honour would be set up.
'I would like to be half as clever as some people like to believe they are' Life is full of disappointments, it is how we handle them that helps to define us, as a person