That comparison can not be made. The push press utilizes acceleration in order to overcome the inertia of the barbell at rest. This allows for larger amounts of weight to be hoisted into an overhead position. In addition, the acceleration and ensuing momentum involved originate as a result of fast eccentrics at hip and knee joint fueled by large muscles at relatively stable joints. During the phase where momentum is present, your comparison to the kipping pull-up, no increases in force, as a result of the momentum, will be exerted on the shoulder girdle. The force applied is going against gravity not with it. Also, a push press is a progression to the split jerk I am not sure what true application the kipping pull-up has, other than what crossfit has dubbed explosive, dynamic and speed. With the kipping pull-up acceleration and the ensuing momentum are present during both eccentric and concentric phases and are directly applied to the most fragile ball and socket joint in the body. The small stabilizing muscles and larger prime movers are subject to fast concentrics followed by a phase where muscle tension is lost, during the transition between concentric and eccentric phases. This is where gravity then takes over and the individual basically falls through the eccentric phase with little to no tension being placed on the prime movers or stabilizers involved. At the bottom the those muscles are then forced to contract once again, with no prior tension, against mass X 9.8m/s/s. This spells out a recipe for disaster when to top it off it is done repeatedly to exhaustion where the little form that does exist has inevitably broken down.
