Low Block - Legal or Foul?

[NVFOA_Ump]

A, 3rd & 14 at the B-21.  A QB is in shotgun at the snap.  Snapper A-51 is blocking nose tackle B-95 who already has 2 sacks in the game.  As B-95 is getting past A-51, A-51 pushes him from side partly spinning him around.  Immediately after A-51 releases B-95 and has no further contact, running back A-25 blocks B-95 from the front (in the 10-2 window) below the knees.

[maven]

C. Illegal block below the waist

Not a chop block without simultaneous high-low contact.

[RunRickyRun]

As a RB, A-25 is unrestricted unless lined up outside the tackle box.  He can legally block a DL below the waist.  The contact was also described as 'from the front' so I assume the contact was 10-2 as well.

A chop block does not always have to be simultaneous, but the two blocks must occur in too close a succession for the defender to defend himself against the second offending block.  Moreover, both blocks must be initiated against the defender intentionally.  In the description, the first block was directed at the defender and definitely affected his path and the second was clearly initiated against him as well.

I've got a chop block.

[psv]

This is legal assuming A-25 is not restricted at the snap.

[James]

This seems very much like AR 9-1-10-II
There it says the OL is disengaging from the block, here it says immediately after.