It sounds to me like the alleged "problem student' is pointing out that the OP is over powering his techniques unecessarily. PS is proactively taking ukemi because he is anticipating damage.

I think there could be some compromise from both aggrieved parties. The OP could lighten up a litte or a lot. PS could let his partner know in advance how much power and force he can manage. I agree with the previous post that practice should be cooperative and that they need better communication.

Work it out between yourselves and try to get along, 'k? That is a good part of what Aikido is about.