It's not just leftist special interests and whacks that are going to protest this. Why? Because it's another case of the parent ceding the responsibility for the rearing of a socially responsible child to the government yet again. That shouldn't sit well at all with the social conservative.
The issue is somewhat less obscured than sex education since despite some seriously antigun folks out there there are significantly fewer taboos associated with gun ownership and handling than genital ownership and handling.
I don't even want the government teaching my boy civics and history. Why in hell would I trust them to make sure the neighbor boy knew how in hell to handle a gun?
The fact is that children today learn a lot about society and life from their teachers in school. I can guarantee that teachers teach their students to look both ways, not talk to strangers, to not hit or harm others (keep hands, feet, and objects to yourself). All of those things are safety related, so why not teach them about gun safety?
For reference, the Eddie Eagle program doesn't bring in guns and have the children physically hold them. The program teaches the children what guns are, that they are dangerous, and if they see one without an adult around to not touch it and to go find an adult.