It is ancient - lorder was to do a topological sort of an archive to put things in "linking order" so that the linker could do a single pass through the library. I think the "lorder" was an option to ar, rather than a separate utility. The way it worked has ar read the object file, then output the external symbols with file name - then the tsort would sort that list and output a list of file names... lastly, the "ar -r" would then put each object file into the library, in the order determined by the topological sort.
I believe you can drop most of that command - replace it with
cat comutil.aix | xargs ar r ../../Bin/libcomutil.a
This should create the library (libcomutil.a), but without the sorting. ld makes multiple passes (if needed) so doing a topological sort shouldn't be necessary. It does slow the link down a bit, but other than that, there should be no other side effects.