Two fins can work, if they're not in the same plane. But yours are in the same plane.
John posted the Guitar video that proved that two co-planar fins CAN work (although they were really THICK fins, not sure how that helped but I think it did.). In this case I see only one fin, the stick piece. The forward side pieces I don’t think are going to HELP provide any stability, although jury is out as to whether they will function as Canards as
@jqavins suggested and make it actively UNSTABLE.
I think John has said he has a private property field to fly his creations, so I am thinking that as long as he stays below the high power threshold he can try anything he wants.
Interesting thought about UNSTABLE rockets. Aside from the fire danger from a rocket coming to earth while under thrust or delay charge (a smoking gun, so to speak), from a physical impact standpoint a severely unstable rocket seems LESSS dangerous than a borderline stable rocket, at least shy of high power. The severely unstable rocket just does cartwheels and hits the ground, it can’t get up enough velocity to impact anything very hard. So mainly a fire hazard. A borderline stable rocket may eventually BECOME stable after it acquires a lethal trajectory, meaning it acquires enough velocity to fly straight, but it ain’t aimed upward. I think this is one of the big fears with multistage rockets, either they go unstable before the upper stage lights and are not aimed skyward, or there is a delay in ignition of the upper stage and the stack arcs over before the sustainer lights.
I am not advocating anyone should ever launch a rocket that they think probably WILL be unstable. Only that on private land (or with full RSO approval and supervision) with non-High Power Rockets it is reasonable to try rockets that are “probably stable.”
definitely should be a Heads Up launch!
I still think this would make a great MonoCopter design, just air foil the stick.