Yes: very low temperature steam is useless from a thermodynamic perspective, cannot be used to perform (meaningful amounts of) work or generate electricity. When sourced a waste byproduct of an electric power plant, it's essentially free—it has no other economic value.
There's zero opportunity cost of "you could use it for some other purpose instead".
Sadly this article doesn't make it clear whether it's waste steam from electricity generation or steam made explicitly for this purpose. It also doesn't specify what the fuel is now - it used to be coal, is that still the case?
Wikipedia says "Approximately 30% of the ConEd steam system's installed capacity and 50% of the annual steam generated comes from cogeneration" i.e waste steam, which is .. half good, I suppose.
There is cost though - the pipes needed to get steam someplace are not free. Those pipes can explode when things go wrong so people can die. How you add those costs up is a debatable question, but it isn't free.
There's zero opportunity cost of "you could use it for some other purpose instead".