We're facing the same issue. The impact of lock/unlock is that all user with HUMO access can lock/unlock handling units. Also it has a delete button there. Only Quality departament in ECC should be able to lock/unlock HU when the Quality tests has been aproved anot logistics or other users. Logistic users should have access to all HUMO except option to lock/unlock HU .
We have tested with security roles but HUMO doesn't seem to have authorization objects and also with variant creation, but we can not see the program/scren that has the lock/unlock option in SHD0.
How did you resolved the issue? or any one has an option to restrict the lock / unlock option in HUMO tx?