> the addition of more luxury apartments will artificially push up the average rate of rentals and will raise continue to make all units in the city less affordable.

Having more units available will mean lower market prices all else equal..

I cannot parse the second half of your sentence, but if you are arguing that having more units will make units less affordable, I (and the relevant literature) disagree that building more units makes units more expensive.

There are 24 more affordable housing units in the city if this conversion occurs, sounds like it'll make a big difference for some people directly and there is strong evidence that adding more units has spillover effects on rents in other buildings. Supply and demand!