Cylinder head torque inspections

Hello, I have a question concerning the 50 hours checks specifically for older generation engines. I would like to understand the reasoning for requiring the cylinder head torque checks to be done only by an A&p,LRSM mechanic and not to be allowed to be check by owners?

According to the JTM001-12 paragraph 2.8 “owner maintenance “2.8 Owner Maintenance; Factory-Built Models have been specifically designed as simple aircraft
which can be maintained by owners to a large degree. Jabiru Aircraft allows normal maintenance up
to 100-hourly servicing to be carried out by the owner wherever this is allowed by the aircraft’s
operating category. This servicing includes: Normal engine maintenance between 100-hourly maintenance.

Arion lightning the USA representative states In their guide for 50 hour checks that: “Note: It is recommended that owner/operators wishing to perform 50-hour maintenance on their aircraft attend a Jabiru USA engine seminar. It is required that they be equipped with a properly calibrated torque wrench and follow the procedures outlined in the Jabiru J230-SP/J250-SP Aircraft Service Manual for all tasks in this inspection guide including engine head bolt tension and propeller bolt tension checks”.

so if the representative believes the owners have the ability to execute this task what is the reasoning for jabiru not to allow it and restrict it to a mechanic or A&p? I feel that there is no continuity between the manuals and this leads to misunderstanding or misrepresentation of the guidance from the manufacturer.Thank you for your response in advance.