This is a really good idea, but it is important to keep in mind that even if all of the steel production in the world (~100 Mton/y) shifted to this method, it would only have a negligible impact on the cement production (~ 4 Gton/y).
https://www.statista.com/statistics/267264/world-crude-steel...
In 2022, a total of around 1.9 billion metric tons of crude steel were produced worldwide.
EDIT: however, your intuition that the impact on cement production would be tiny is correct.
This report indicates that producing new steel from ore requires about 270 kg of limestone per metric ton of steel, or 88 kg of limestone when recycling steel in an electric arc furnace:
https://worldsteel.org/wp-content/uploads/Fact-sheet-raw-mat...
World steel production is about 35% recycled, 65% new from ore. So this new Cambridge research, which applies to recycled steel, could displace about 59 million metric tons of limestone consumption. That is small compared to billions of tons of global cement consumption. It might be locally significant for municipalities that have electric arc furnaces for steel recycling.