The typical rule of statutory construction is that if newer laws conflict with older laws, the newer laws control.
True, but when the newer law expressly acknowledges that previous laws remain valid and in effect (which is what 1289.6.A.6's reference to other "legislative enactments" concerning firearms does), there would be no conflict, so that rule would not apply.
Also, 1272 contains this exception to the prohibition:
2. The carrying or use of weapons in a manner otherwise permitted by statute or authorized by the Oklahoma Self-Defense Act;
which would include 1289.6, which is the only way it is legal to open carry while hunting, target shooting, or any of those other activities listed in 1289.6, including "for any other legitimate purpose."
I agree that this is the knottiest part of the issue. 1289.6.A.2 flat out says that (e.g.) "target shooting" is a permissible purpose for open carrying, so open carry for that purpose doesn't violate 1272 either, since 1272.2 has an exception for "the carrying of weapons in a manner otherwise permitted by statute," and 1289.6.A.2 is a statute that says open carrying while target shooting is a permissible manner of carrying. Agreed.
But in contrast, 1289.6.A.6 doesn't say open carrying "for any legitimate purpose" is permitted. The provision doesn't end there. Instead it says, "for any legitimate purpose not in violation of ... any legislative enactment regarding the ownership, use, or control of firearms."
So where does that leave us? 1272 says in effect 'all handgun carry is illegal except for the specific exceptions given here [which don't include self-defense], and except for when another Oklahoma statute says carrying them is allowed.' So if 1289.6 simply said that open carrying for "any legitimate purpose" is allowed, full stop, then you would be right. That would mean another Oklahoma statute (1289.6) had affirmatively said you can open carry for self-defense (a legitimate purpose), so open carrying for self-defense would fall under the 1272.2 exception and would not be prohibited by 1272.
But that's not what 1289.6 says. It says you can carry for "any legitimate purpose not in violation of" other OK statutes on firearms. Well, 1272 bans open carry for self-defense unless another OK statute affirms that such carrying is legal. And 1289.6 hasn't really done that. 1272 directly bans all carrying unless an affirmative exception applies. The way 1289.6's "any legitimate purpose not in violation of" clause is worded indicates that it is not intended to modify the background prohibition of 1272.
Put more bluntly, 1272 says "no carrying a particular way unless some OK statute tells you it's allowed." The other parts of 1289.A (target shooting, hunting, etc.) do specifically state that open carrying for those enumerated purposes is allowed. So they are carved out of the prohibition in 1272. But 1289.6.A.6 says (in effect) "any legitimate purpose that doesn't violate 1272." That doesn't modify the prohibition in 1272. If the way you're carrying would have violated 1272 in the absence of 1289.6.A.6, then the existence of 1289.6.A.6 doesn't change that outcome.
Again, I agree that the law is a mess in this area. This is one reason to support HB2522, which would at least clear this up to an extent by expressly allowing loaded open carry for self-defense, without need of an SDA license, on one's own property.