No, "unlocking" in this context refers to the baseband lock which prevents your phone from joining another carrier's network. This form of lock vastly predates phones with customizable OSes and was originally in place to prevent customers from receiving a subsidized phone, re-selling it for use on another network, and then breaking their contract, or trying to arbitrage a margin between early termination fees and remaining phone cost.

This guidance requires that phone companies allow their phones to join networks they are technically compatible with (i.e., have the radios and baseband support for). It's generally unrelated to the OS or bootloader, as this form of lock is often implemented at the baseband level.

The issue is that phones can be "unlocked" (made able to join another network at the baseband level) but non-configurable at the OS level, barring features requiring OS configuration, like MMS, from functioning. This doesn't seem to be specific enough guidance to prevent phone carriers from playing this trick, as they can continue to provide technically unlocked phones that don't work properly on other networks.

This doesn't really change much these days as the US market is gradually moving towards a financed (rather than subsidized) phone sales model where early termination fee arbitrage isn't possible and collections for broken contracts are more conventional. In general, carriers have less of an incentive to carrier lock their phones than they used to. Plus, some carriers (like Verizon) are already required to supply their LTE phones unlocked due to agreements made to acquire spectrum licenses, so this doesn't really affect them.