We had a similar situation when the Committee decided they didn’t want large trucks using the driveway so they put a height barrier at the entrance, without approval from the owners. They refused to remove it until an owner who is also a lawyer put the case. IIRC the points he made were:
The owners own the common property, not the SC.
The owners have a right of access to ‘their’ property.
Any change that restricts that right of access in any way must be a decision of the owners, not the SC.
The Committee thought about this for a while and reluctantly agreed, and took the barrier down. They might have got some other advice of their own, which would have been the same. The reason for the concern in this case was the impact that not being able to bring a furniture van to the front door might have on resale prices (a fire engine would have driven straight through the barrier).