This is legal by rule 3.3.6.b.
Don’t think of it as a suspended roll. It would be illegal as a suspended roll since a suspended roll requires an upright base.
This is a standard “inversion below prep level” where there is one person on the wrist, which meets the requirement of “at least one person shall be in a position to protect the head/neck of the top person and shall maintain contact with the top person’s upper body (waist and above, which may include arms/hands)”
The person on the ground is irrelevant from a rules standpoint.
This is exactly the way the skill must be done in order to be legal. If the person on the side was not in contact, then you would not have a person 1) on the upper body AND 2) in a position to protect.