[Crakkerjakk]

The only problem with this is you don't have to do this in real life if you have a limb grappled. You can remain standing if you have a leg or arm in a lock. For torso or head, I would say you had to be a step removed from the targets posture(kneeling for a prone target, etc.)

However, on a strictly rules interpretation, the Judo skill itself (B203) says nothing about having a grapple when executing a Judo throw. All it says that after a successful parry, you may attempt to throw them. So, looking only at Basic, I would say that the Judo throw is itself not a grapple, and therefore you do not retain a grapple when tossing someone to the ground.

Adding in the MA text on MA75, I would say that you only retain a grapple if you first grapple your opponent, and follow that up with a throw, per the rules on MA75. In this case you only lose the grapple on a critical failure. From my personal experience, it's not that hard to hold on to part of someone you are throwing, as people tend to cling to things when they get lifted into the air.

*EDIT*
And mook, to address your question specifically, I would interpret it as, if you throw someone while grappled, you may remain standing if you have a limb or change to kneeling if you have a head or torso. If you are attempting to grapple with them already in another position, you must do so in the same posture they are in, as you don't have the option of just hanging on as you toss them to the ground. Excellent work on the combat examples, btw. Really interesting stuff.