I don't know when section 626.10 was written, I'd have to ask my attorney, but it's been this way for as long as I can remember. Here is a link to that statute direct from the official California legislative website-
http://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?sectionNum=626.10.&lawCode=PEN
The statute is pretty clear about what is illegal. And what is not illegal, is legal.
As I said in the post you quoted, schools can make their own rules that are more restrictive than state law (like "zero tolerance" policies). A student who violates such a policy can be expelled. But as a parent, I have no fear of expulsion.
Well, my attorney is very knowledgeable about such things. And he has assured me that a person can only be arrested for violating A LAW. A person cannot be arrested for violating a
school policy.
My attorney has also assured me that as long as the knife I carry onto school property is not illegal under California state law (we have no city or county knife laws in San Diego), then I cannot be arrested and charged with any crime for carrying such a knife.
Furthermore, I have used my knife countless times at school functions. Both for personal reasons and to help set up for events. And no one, staff member or parent, has ever said a word to me about it, except to ask me to cut something for them, and thank me for cutting something for them. And that includes one of the other fathers who happens to be a police officer.
So no, being arrested for carrying a legal knife onto school grounds is not a concern that I have. But unlike the OP, I'm not a high school student in Colorado. I don't know what that's like, and I haven't had my attorney research that subject as I am not likely to find myself in that situation.
The OP is correct about it being legal under Colorado state law to carry a knife onto school property as long as the blade is no longer than 3.5". But it's entirely possible that his school might have rules of their own. And it's certainly his responsibility to check on that with a reliable source (as in, school administrators).