Inertia's Special Power reads: "Opposing characters that are given a non-free action within 6 squares of Inertia replace their speed value with half their unmodified speed value for the action" The Judge ruled that if an opposing character started their moment further than 6 squares away that Inertia's Special Power didn't affect the opposing characters speed when that opposing character became less than 6 squares away from Inertia. Is this correct?

That was correct.

The power is only checked when an opposing character is given a non-free action: if they are not within 6 squares when given that action, the SP has no effect.

Correct. You are given the non-free action at the begining of the action, so before you are within 6. After you move to within 6 the action has already been given, and Inertias power reads, "Opposing characters that are given non-free actions WITHIN..." Makes sense?

EDIT: Sigh... Ya know, when I don't try to answer stuff it seems to take orange longer... Hehe messin.

Probably could be another thread, but...

What about Harry Leland? Would they just stop their Hypersonic power portion of their movement (still being able to finish their movement value of course)? Or is this the same?

"MASS INCREASE: Opposing characters within 4 squares of Harry Leland can't be given actions to use Charge, Running Shot, or Hypersonic Speed and halve their speed values when given a move action."

I bolded the important parts of the text.

In other words, the answer is the same. (If you start more than 4 squares away you can HSS, Charge, or Running Shot to your heart's content.)