They're membership partner from what I can see.
Your logic is undone by the Storm's training gear having a bunch of different companies on it anyway.
That's true but they have been a membership partner for a while now.
And no, my logic is not undone by the Storm's training gear, they have most of their sponsors on their gear, Souths do not. In recent times, we have tended to only have our main sponsors on the off field gear and I don't think 2019 will be any different. That's not to say it definitely won't be different but I don't expect it to be and I think P&O are now one of our primary sponsors. Still speculation at this stage though, I guess time will tell haha.
On that note, I wonder why us and the Storm are taking so long to release actual playing jerseys, all other ISC teams have released stuff. In fact, I think we may be the only two clubs left that are still yet to release an actual playing kit for 2019. I'm growing impatient lol!!