Doubling UTXO capacity doesn’t change the core point in this model.
Sooner or later the state will grow. That is part of the protocol design. If you can fill every block for months, generate more than 100 million wallet proofs and burn the required NOID, feel free to speed it up by spamming the state. That is paid-for state growth, not the cheap attack you described. All NOID holders will thank you for your work

The State-growth fees are not burned — they are paid to miners.-- State-growth fee: 2,500 uNOID is burned
https://github.com/ignotusnemo/parano1d/blob/main/noid_chain/src/consensus/fees.rs#L141-L158From the miner's perspective, the attacker keeps the non-burned transaction fees.
Only the State-growth fee is burned.
Non-burned fee: 5800 uNOID = 0.0058 NOID
State-growth fee burned: 2500 uNOID = 0.0025 NOID
Total fee: 8300 uNOID = 0.0083 NOID per transaction
First halving:
0% -> 50%
State-growth fee: 2500 uNOID
Total fee: 8300 uNOID = 0.0083 NOID per transaction
50% -> 75%
State-growth fee: 5000 uNOID
Total fee: 10800 uNOID = 0.0108 NOID per transaction
Transactions required:
8,388,608 + 4,194,304 = 12,582,912 transactions
Total fees paid:
8,388,608 x 0.0083 = 69,625.4464 NOID
4,194,304 x 0.0108 = 45,298.4832 NOID
Total fees paid = 114,923.9296 NOID
Non-burned fees returned to miner = 12,582,912 x 0.0058 = 72,980.8896 NOID
State-growth fees burned = 8,388,608 x 0.0025 + 4,194,304 x 0.005 = 41,943.04 NOID
So if the attacker also mines the transactions, the miner's direct fee cost is only 41,943.04 NOID.
41,943.04 NOID = $335.54 at $0.008 per NOID.
The block reward then drops:
50 -> 25 NOID per block.
The attack requires about 49,345 blocks, assuming 255 net-new UTXO transactions per block.
At 20 seconds per block, that is about 11.42 days of cumulative theoretical block time.
This does not account for the actual time needed to produce the blocks,
which depends on the attacker's hash rate and probability of finding 100% of the blocks.
For comparison, using a 45 NOID block reward:
Average State-growth cost per block: 41,943.04 / 49,345 = about 0.85 NOID
Block reward: 45 NOID - 0.85 NOID fee per block = 44.15 NOID per block
Total reward: 49,345 blocks x 44.15 NOID = 2,178,581.75 NOID
Value at $0.008 per NOID: 2,178,581.75 x $0.008 = $17,428.65
Actual State-growth cost: 41,943.04 NOID = $335.54