"Senior" at Bloomberg certainly used to be (when I worked there) a title used to distinguish between [just-graduated] hires and [everyone else]. The cut-off was explicitly two-years out of university. It had very little to do with true real seniority within the R&D tech organisation/hierarchy.

I'd guess at the poster not quite realising this themselves. It certainly used to be the case that the many fresh new graduates we recruited annually took quite some time to learn how much they didn't know.