The key here (under IPSC rules) is that the Patriot Defense guide rod constitutes an aftermarket part. Hence, as @Kiwishoot correctly notes, it would not be legal. See Special Condition 19 (et al) on the page he references.
I would note, however, that if Tanfolglio were be the ones making this part it would be legal for guns they make for which it would be intended to fit. See Special Condition 18 (et al), same document.
JMHO, but I think that's a little nuts ...