Dear Parental-Seeming Person,
I recognize that it's really hard to keep control of your four or five year old in the store. I can't tell you how to do it; my inability to figure out such things contributed to my decision not to have kids. Alas, it didn't do so for you.
But seriously, maybe you could just pick up your kid and prevent him from opening at least one deodorant stick of each type, pulling off the plastic guard thing, touching the deodorant and putting the stick right up to his snot-encrusted nose for a good sniff.
Maybe it's time to recognize that telling him repeatedly not to do that isn't working and actually take some action, now, while you're bigger than he is and could actually pick him up?
PS. I'm really hoping you two weren't in the veggie aisle.