Actually, it's read by the exec() system call (in sys1.c).
To be fair UNIX was the naming sinner here IMO. Unix's ld command is the "link editor", and exec(2) is the "program loader" in the pure OS/academic naming sense. I never asked Dennis or Ken why those names were not used. I suspect like creat(2) it made sense at the time and then by the time the functions leveled out, it was embedded too deep the change it.
BTW: the DEC (vms) link editor runs on Ultrix (PDP-11 and Vaxen). The binaries are part of the Fortran kit. I'm not sure if it will run on V7 but it might work on BSD 2.x. It's author sits a few feet from me these days. When DEC finally went to support DEC standard Fortran on UNIX it was just easier to make the VMS link know how to output an a.out (and macho files) and the end, then it was to try to add the features they needed for Fortran to ld and a.out.
It's interesting hearing from Paul his issues over the years between, Unix, NT, Apple etc., a.out, COFF, and other formats.