That makes a lot of sense. When there was a name, it was preserved, but a huge amount of the sources had nothing at all in the source files to identify it. One big area of contribution was into the kernel where the options sometimes contained the name of where the code came from. In the 2BSD kernels we see eg TEXAS_AUTOBAUD, MENLO_OVLY, MENLO_KOV, MENLO_JCL, MPX_FILS, CGL_RTP and a bunch of UCB_ names. It's clear the non UCB ones came from elsewhere, but there's no info on where they came from (they are documented in setup.5 at least so I know what they are). So given the sparseness of the early marking for provenance, the coments make more sense and give a better timeframe to it.