I'm not picking up any subjective, simplistic labeling like "good" or "bad." Are we reading the same paper?

Haven't fully read the paper, just the introduction and skimmed through the rest, but it seems they're merely observing that a rent control law went into effect, and given some control variables, it seems like it depressed property values.

Their findings also suggest that while the wealth transfer of rent control factor is real -- that is, landlords are impacted more and existing renters see relative benefit -- that effect is greater among higher-income renters and less among lower income renters.

Second paragraph in the Conclusion:

"While the negative wealth effects for owners are large, our results show the positive effects of the law are poorly targeted. Though the intention is to benefit lower income renters, we find that the largest benefits are received in the neighborhoods of the city in which renters have higher incomes, are less likely to be minorities, and have more education. To the extent that price drops for rental properties reflect future rent savings, and thus housing wealth gains for tenants, our results suggest that the largest cost savings are going to be realized in the neighborhoods with the richest, most educated, and least diverse owners."