This argument is predicated on Anthropic losing money on the subs, but I'm not sure that's a cut and dried argument. OpenAI have said publicly that they're (very) profitable on inference, and they're much cheaper than Anthropic. I suspect this is just artificially trying to create a moat. The problem is their moat is not as sticky as they think it is - I completely ditched Claude for Codex a while ago, my money now goes to OpenAI, and I'm very happy with it. For a while Claude was noticeably better, but that's not the case any more - in my case I prefer Codex.
They aren't public companies (yet). They are allowed to just lie about these things. It's also not really reasonable to only count inference compute as a cost since it's not like any of these companies could stop doing R&D without being abandoned for having worse models within a year or 2