Safety - Touchback - Forward Progress?

[Base]

Originally posted by Theisey
I'm sure that they are without a doubt talking about a defensive player that is the person "holding" up the runner and therefore the only way you get forward progress is this way.

But if you insist on holding, than when a runner runs from his EZ and is tackled (pushed; not held!) on own 2 so hard, that he flies 2y into his EN, where the ball becomes dead, you would rule safety. I believe, that when determining FP, opponent´s action should be considered, although it´s not explicit written.

So, in the origin example R-ball on 2.5. This example A-ball on 2. That example with runner being tripped by teammate: safety