If you exclusively consider the value of the puts, then yes they made a killing. But Mexico didn't use the puts to take a huge directional speculative bet - it used them to hedge oil price risk, so the profits from this trade are structured to offset losses elsewhere. For example, sustained low oil prices will could put companies out of business or even make Mexican oil uncompetitive on a global scale.

Yes an absolute killing, similar to the one mentioned in the article for back in 2008 - may not be as much as back then but still a lot.

This is a case where a hedge plays out well, and the main motive for their play is stability for their government spending. Good for the citizens of Mexico