Withdrawing from pre-tax retirement accounts counts as income for ACA purposes. You've now lowered your annual expenses (and thus, your income) and can qualify for subsidies, but all you've really done is shift some of your net worth from investment accounts to housing, in order to reduce annual expenses. This example is likely more applicable to a person in retirement, as well.
I don't doubt that for people with some money, it'll be common to countdown using similar strategies for 5-10 years until you hit the magic 65 age. Given the difficulties in staying employed until full retirement age for programmers, it's quite a gift.
In another couple of decades, a lot of people get to do the pay-down fandango where couples split their assets so that one doesn't pauperize the other (via annuities).
All brought to you by the market warping body called government.