The article states that /bin/ls is statically linked. That means that the parts it uses from libc have long-since been taken and merged directly into the ls binary. So this randomization has no effect.

Even if ls were dynamically linked, the ls binary itself wouldn't change at every boot; instead its import/jump table, generated dynamically by ld.so as part of the OS's executable loading process, would simply point to different (and random) offsets within libc. It would have a different in-memory representation after each boot, but its on-disk representation would remain the same.