He would have greatly increased his chances. Assuming that the agent used was run of the mill V/G agent and not a specialty delivery variety.
In reality atropine and pralidoxime(antidote sorta) administration would have most likely saved him, but it would be very unlikely for a medical professional to deduce that the threat was cholinesterase inhibition(nerve agent poisoning).
Atropine is commonly used to treat other medical conditions. I would expect any modern emergency medical service to have it on hand (though perhaps not in the quantities necessary... we would need to use all the Atropine on multiple ambulances to treat one patient in this condition).
No, they essentially work to solve the same problem in different ways.
To use a very clumsy analogy, imagine nerve agents like VX are slamming on the brakes of your body. Atropine makes your body less sensitive to the effect of "brakes". 2-PAM takes the foot off the brake.
In reality atropine and pralidoxime(antidote sorta) administration would have most likely saved him, but it would be very unlikely for a medical professional to deduce that the threat was cholinesterase inhibition(nerve agent poisoning).