It's still inductive, because the premise is based on an observation or survey. "Studies show that crimials avoid people who was armed" does not mean the next one will.
As the saying goes "the race is not always to the swift, nor the battle to the strong" but that's the way to bet.
Nobody has claimed that the deterrence factor is a panacea, that it will always work all the time on every possible criminal. Therefore the whole "does not mean the next one will" is a red herring.
It doesn't guarantee that the next one will but one doesn't have to have a guarantee to have the odds improved.
In deductive reasoning, true premises guarantee a true conclusion.
It should be noted that deductive reasoning can never generate "new" truths, therefore all genuine experimentation or empirical research will of necessity involve elements of inductive reasoning.
Basically the concusion of a deductive argument for open carry will be "Criminals will not attack a person who is armed."
We know that's not true.
Since nobody has made this argument, it is again a red herring.