Sure, languages evolve, but that doesn't mean "anything goes" -- to the contrary, novel mutations have to survive intense selection pressures in order to eventually become part of the standard language.
Where new ways of using existing terms create ambiguity and conflict with existing meanings, their survival chances aren't always great.
This use of "bare metal" does contradict the pre-existing meaning, so is not quite appropriate. What is valid is describing the OS itself as running on bare metal in contrast to running within a VM/container -- but an application running on top of that OS is not running on bare metal.
This isn't particularly egregious, though, since there are negligible cases of actually running applications on bare metal today: if you are talking about applications, the context can usually explain the intended meaning. But that wasn't always the case in the past (PC "booter" software used to be common), so this doesn't necessarily apply retrospectively, and may not be the case in the future, especially considering some of the interesting things companies like Oxide are working on.