In the year 2140 we start stealing the coins which have been not moved since January 2009.
In the year 2144 we start stealing the coins which have been not moved since February 2009.
So at an average rate of 4,320 blocks per month, this means you would release coins at a rate of 3 blocks per day every 4 year period. So that first day will see (we assume) 150 BTC released. Now, let's say the total block reward from fees alone is 0.5 BTC, which is probably a high estimate. This means 72 BTC a day from fees, and 150 BTC a day from releasing old coins. Every large miner is therefore incentivized to ignore blocks from other miners claiming the old coins, and instead continue to mine blocks on their own chain claiming the old coins for themselves.
Also, the very fact you use the word "stealing" explains it all, really. At no point should the protocol ever steal coins from other people. There is a huge difference between a random malicious actor with a quantum computer stealing coins, and baking stealing coins in to the bitcoin protocol.
In the year 8428 we start stealing the coins which have been not moved since January 2140
What happens when bitcoin has become so valuable that the total amount of coins not moved since January 2140 is a few hundred sats at most? The whole system collapses and you are back to only relying on the fees.
This is not a solution - only a delaying tactic, and one which would fundamentally alter the entire concept of bitcoin.