Yes, ABN will affect POG, but only to the degree that you are actually solving blocks.
If you had 256,000 total coin*age in the wallet, and you create an ABN for 128k, you still have 256K coin*age for the GSC transmission for POG (If you didnt solve a block).
But if You did solve a block before the gsc transmission hits, the GSC txid creator would only have 128K to work with.  If your GSC percent is set at .50, it would only be able to send a GSC of 64K coin age.

You can also type 'exec createabn nnnnn' with the amount you specify (such as 128000), and it will show you which coins are allocated toward the ABN, and that would give you an idea which coins would be spent (if you solve a block) and not available for the next gsc.

So basically:  Pog & ABN share the same UTXO base.