What about the 2nd part of that article? Did Cunningham indeed get a way with a Palmer/Brady-rule violation?
I looked at the linked replay and it's certainly true that after going down, Cunningham crawled forward and grabbed Sanchez's ankle and calf.
Here is the rule emphasis that he is discussing:
The fifth provision of Rule 12, Section 2, Article 12 (roughing the passer) says that: "A rushing defender is prohibited from forcibly hitting in the knee area or below a passer who has one or both feet on the ground, even if the initial contact is above the knee. It is not a foul if the defender is blocked (or fouled) into the passer and has no opportunity to avoid him."
Fisher said the feeling was that a play like the one Pollard made is one that can be avoided.
"It's a player that's down and then he does that second act where he's getting up and intentionally rolling into the quarterback, or where he's getting up and he lunges at his legs," Fisher said. "We've got a lot of shots where guys have gone down, crawled, and swiped. We don't feel like that's potentially as injurious to the quarterback than the hit where the shoulder comes down to the knee or the planted leg."
I think Fishers second comment as it describes pretty closely what Cunningham did and seems to say that isn't illegal. The actual rule states a "forcibly hitting" which again is not what Cunningham did. I think the reason that Barnwell sees all these plays without penalties is because he is misinterpreting the rules.