PTA rules that have been written are emergency rules and they don't go into effect until the PTA's become regulated in June. They were posted in March which allowed time for review and comment.
http://www.dora.state.co.us/physical-therapy/EmergencyRules_PTA.pdf.- click this link to read the actual rule
Joint Mobilization Debate
It is accurate that the Rule was written that joint mobilization is prohibited UNLESS the PT determines that the PTA meets certain criteria. APTA's position from the national House of Delegates is that PTA's should not be allowed to perform Joint Mobilization (any grades). Despite this position, there are inconsistencies across a variety of states.
Current Rules in Colorado (have been in place for 7 years) do not prohibit PTA's from performing joint mobilizations. The rules are silent. (There is a Rule that specifically states that PT aides can not perform joint mobilization.)