It sounds like you have a game plan, Mike. Good luck with the Ninja, they're excellent teaching bikes. No matter our experience level, we all need to be in a state of learning.
More to Alex' point, braking while in a lean is pretty accepted when riding a sportbike; it's something that is done while trail-braking and certainly not something to avoid. I agree with you that nobody is going to recommend it in 20-degree weather on old tires. You did that
and, as you said, you learned from it.
Have fun and don't let any keyboard warriors distract you from
riding. That's what we're here for. Alex too