And the important thing to remember about the $500k is that it was evidence of financial commitment and capacity to finance a H&A national league, in the form of a bank guarantee.
A 10 team, 18 round home and away league will cost about $1 million in travelling costs, assuming the two additional teams are from anywhere but Perth or further north than the Sunshine Coast (and not from VIC or NSW). The cost for NSW and VIC clubs (given they have more away games in the same city) is about $80k and $120k respectively, and about $150k to $190k for interstate teams, depending on whether the 9th and 10th clubs are from the same city or not.
The reality is, you need clubs who can afford to cover that expense, and the FA would be irresponsible if it didn't ask for evidence. When we get to a full H&A Championship, the reality is that it will include teams that can afford the expense, not simply those that finish first in their respective NPL. The JFA did the same when it formed both the J2 and J3 leagues - it brought in clubs that had associate status (they had the funds, structure, and facilities that met the JFA's criteria for those new leagues), not the best performing teams from the semi-pro JFL. Only after 25 odd years do they finally have relegation to the JFL from J3, but it only occurs when an approved/accredited club finishes 1st or 2nd in the JFL. If that doesn't happen, there's no relegation from J3, regardless of how dominant the JFL league winner was.
It's worth noting that this is basically the same principle across the globe. We don't really see it in action much in Europe because they have so many professional clubs and/or semi-pro clubs pushing to get promoted, and so have the off-field stuff in order before their performances warrant promotion. It happened in France a few years back with Luzenac gaining promotion to Ligue 2 but being denied entry because their ground wasn't up to scratch. Even in England, all clubs have their ground graded every few years to inform clubs what they might need to do to stay in their current league, or what to do if they're seeking promotion to higher levels.