I dont understand why you think the definition belongs only with momentumtime  the reason is pedagogical within the physics discipline  it would be a tautology to define the Joule as the amount of energy required to move a body against a force of  Newton the distance of  meter then at the same time define the Newton as  Joule per meter  its true but it says nothing about the quantities of the Joule or of the Newton nor anything about their dimesion  it is not like the chicken and egg we know which one comes first meter kg second come first then the Newton before the Joule the Planck force is a derived unit and will have to be the Planck unit of momentum divided by the Planck unit of time  the fact that it comes out to be the basic tension in string theory or in general relativity the force that is the conversion factor between spacetime curvature and the energy density giving rise to it or if multiplied by the fourth power of the dimensionless circular orbit speed some distance from a central body that it tells what the body would weigh at that distance all these are fine and good but they are the result of working out hypothesized physics problems they are not the definition  what if you worked out some other basic physics problem say the basic tension of a string and it came out to be  FP or   FP  would you say that the force solutions to such are the definition of the Planck force  it doesnt matter what the system of units are once you have those  base units defined there is no freedom left to define the others  their definitions are purely consequential  i think you need to word things according to the most common terminology  i fixed it a little more  i inserted edit notes invisible that ask what does it mean to distribute energy over a gravitational radius and what does it mean to distribute energy over the Compton wavelength  unless you expect your encylopediac readers to know even vaguely when or where or how or why such distribution of energy is being done thus defining the rate of such distribution why say these words  also there still is no citation other than Schwartzchild radius which i did  so a reader does not think that this was all just made up you might want to include references to other stuff  i fixed the convention errors and format errors some just now  do a diff comparison to see what i did