I'd much prefer a solution that benefits lower and middle income people, but this proposal is a pragmatic one.

He’s giving them millions (I think actually billions) for them to make those office spaces trendy expensive condos most people won’t be able to afford.

That will certainly be some, but I doubt even a majority of the final residence of these converted buildings. First, there just aren't that many rich people that will buy a multi-million dollar converted office building residences. When the market for the rich is exahusted, there's likely still plenty of converted buildings which means the price per unit declines to more reasonable (not cheap, admittedly) housing costs. This has a knock on effect with the entire residential real estate market. Existing housing will get cheaper everywhere just because the larger supply of housing inventory appearing essentially out of nowhere (because offices took this land off the residential market decades ago).

Further, people want amenities around their residence. Things like grocery stores, restaurants, dentists, etc. With enough people (of any income level) these services will start to appear. So lots of jobs, and if housing in this area for workers, then the salaries of these workers will have to be raised significantly higher to get staff.

So with one macro decision, lots of this can occur.

Rather than telling the disgustingly wealthy people that own those offices to pay for it themselves while prioritizing affordable housing for people who need it.

The large majority of office owners won't make this conversion on their own right now. So what you're advocating for is for all those buildings to sit empty for possibly decades. So do you want that housing to exist now or 20-30 years from now when each developer slowly makes that choice. This is the ugly, but pragmatic, reality about getting change in our society.