I fully agree that finding an existence proof of RTSC could also fail to achieve anything, and even not affect rent at all- absolutely zero change in the two world lines.
Let me rewrite my original sentence that bothered people, so it's a bit clearer. Here's the original:
"""Room temp Superconductors, along with fusion, would affect the economy profoundly. What the exact effect on rent would be is hard to predict but under the "post-scarcity society" mental construct, having infinite energy at zero cost (amortized) would presumably make the price of housing change."""
Change "would" to "could" in the first sentence to make it conditional. Add an additional sentence at the end pointing out that house prices are complex and many factors influence them, and another pointing out that while sometimes we can achieve a property in a material, but fail to realize its industrial potential".
It does seem reasonable to posit that RTSCs, even if they failed to realize their industrial potential- could have an affect on rent. Rent is (to a zeroth order approximation) determined by a wide range of macroeconomic activities, and if we reordered our entire society around improving RTSCs, that could have indirect effect on the cost of housing.
All of that was implicit in my original text- and I had hoped to make that clear- rather than making a strong statement like "rent will go down if RTSCs exist".