I had to go back and do some research on this because I wanted to make sure I wasn't mis-remembering.
But: He hasn't capped in five years and wasn't involved at all in the 2018 WC cycle, hadn't scored a goal in World Cup 2010 (the only one he was on the squad for) or Euro 2016, never scored a goal in a UEFA Champions League match and only played a few of them with Marseille and of course, never left Ligue 1 (in his defense, that was largely against his wishes). Also in Gignac's defense, France has obviously been loaded for the last 5 years, and sure runs circles against anyone we can claim as a USMNT #9 today.
While there's no doubt a player can come overseas and enjoy a renaissance, I see Gignac's success well into his 30s on this continent as a feather in the cap to the Euro-snob. I guess that's all a long-winded way of saying that Gignac had been a very mediocre player on very mediocre clubs in a very mediocre league, and I think it was hardly a coup for Tigres. I'm guessing he (hopefully) may take a swan song somewhere back in France on a loan or a free to end his career.