You have to be very wary of Personal Services Income provisions under the ATO rules. You might need some professional advice to make sure you don't get caught out on that score. Lots of one person Pty Ltds get caught out.
I think the poster would be OK, actually. It sounds like they have income coming from several unrelated entities, have the right of refusal for work and a few other things like that. The only things that indicate PSI are: they probably get paid when for fixing a bug that they created; they are probably paid on submission of a timesheet. But overall, it sounds more like a consulting business than an employment arrangement.