My take, and just an opinion because I really don't know, is that the licence fee and security payment in case of a bad run for the club are the same thing.
It really doesn't matter if the NRL hands it to clubs as a membership fee, sticks it in the bank or buys a hotel with it, because the game as a whole is on the hook for bailing out a new club if they go broke.
This is why a new entity like Perth has to pay and a rich, existing club like the Dolphins didn't, because they clearly demonstrated that if things go badly, they had their own significant cash reserves and asset base to fall back on.