Rather than experiment, just stick with what works.
For long term storage, you have two options. Drain the fuel tank and carbs, and spray the carbs with fogging oil, and pour some motor oil in the fuel tank and swish it around to coat the walls.
OR
Add sta-bil or seafoam to the fuel. Drain the carbs and add fogging oil. Keep the fuel tank full to prevent internal corrosion.
What you do NOT want is any combination of unstabilized fuel or fuel tank metal exposed to moisture and corrosion.
Your friend with his two cycle oil is doing exactly nothing. The fuel system doesn't "need" lubricating and it's DESIGNED to work with gasoline. A fuel stabilizer can help prevent the fuel from varnishing with long term storage. Gasoline is also a solvent, meaning any tiny bits of two-cycle oil that might cling to some component would then immediately get flushed out and burned in the engine by the gasoline. I can't even begin to fathom what your friend thinks is "happening" by adding two cycle oil to the fuel tank, other than risking his fuel pump and injectors (a carbed engine can tolerate oil, such as fogging oil, in ways that a high pressure fuel injection system cannot) and wasting some money. Absolutely nothing positive will happen or could happen.
I'm genuinely scratching my head as to why someone things the internal fuel system needs "lubricating" and why they think oil is what'll lubricate it. Take some motor oil, just a dab (which is an order of magnitude more than the oil that would actually touch the fuel lines in that situation), and pour some gasoline on it. No more oil. Even if he ran a straight up 40:1 two cycle oil setup and, through some miracle, his fuel system survived such abuse; the very next tank of gas would completely break down and dissolve all of the oil within the first few minutes of driving. (And then it would run MUCH better because it wouldn't have the added FRICTION and TENSION of oil doing the OPPOSITE of lubricating. Fuel running through tubing is not the same as two metal parts rubbing against each other). No offense to your friend but that's just... the weirdest thing I've ever heard of and kind of the strangest example of the at-home chemist I can think of. It's not uncommon for people to want to mix up magic potions in their oil and gas tank to give some perceived advantage (usually, they are doing more harm than good); but that one takes the cake, ha!
AND, if the idea is to add oil to the fuel to protect the tank; again, gasoline is a solvent. If the tank is full, it will not rust. If the tank is half-full with oil and gas, the top half could still rust because no matter WHAT is in the tank, if it isn't touching the walls of the tank, it can't protect it. The manual suggests motor oil because STRAIGHT motor oil not in the presence of a solvent like gasoline will cling to the walls of the tank. However, leaving the tank full is just easier because when the walls of the tank are covered with gasoline, moisture won't harm it then either.