bootloader doesn't need to be unlocked, it does make it easier, but, a bootstrap work-around can be used. there is a custom bootstrap work-around semi-working. it will allow packages to be flashed, however, there is no way of booting directly into the recovery and if there's a problem with a flash, you cannot boot into recovery and restore from a back up.
current process on other moto devices using this bootstrap work-around have a factory sbf, so if there's a problem, they reflash back to factory, reroot, re-install the custom recovery, then they can restore from their nandroid backup. but since there's no sbf available for the atrix 2, this is not possible for the atrix 2 owners. which makes flashing extremely risky at this point.
once the first OTA update is pushed to the atrix 2, this should give us access to a factory sbf file that we would be able to flash. this will eliminate the the risk of a never-boot situation. that is of course, the custom recovery isn't solved by the time an update is pushed out.
an sbf will also make life easier for devs to have a base rom to build from as well.
so you will see a custom recovery and custom roms either soon, or shortly after the first OTA update.