Indeed, and yet it may also work.

The "creepyness" rules are not formulated to make one effective at social interaction, they are formulated to prevent creepy behaviour. Those goals may conflict.

More cynically (not necessarily my opinion), the stated rules are damaging to people who follow them, because when people think them up, they think of someone they wouldn't like, and then think of rules that they would like such a person to follow. No incentive to think of the misliked person's best interests.

borderline-creep behavior

I suppose some women could misinterpret it this way. But given that "we see and greet each other occasionally" she should be brave enough to refuse your unsolicited umbrella if she felt uncomfortable. But yes, you would be running a bit of a risk.

A non-sudden matter-of-fact move with a few words can help reduce the chances of that, especially if it's all done in a certain Notice ->BeginHelping / ShowYouCanHelp -> GiveAnEscapeRoute+OfferMoreHelp pattern.

If someone is carrying heavy bags and looks like they're about to fall a flight of stairs, I put up my arm to help and then ask if they want help, or some other signal of offer-for-assistance that gives some kind of opening to say "No thanks" or walk away.

If your actions and/or words pattern-match to this kind of intervention, then the vast majority of people will look positively upon it, IME.