Earlier quoted context omitted.
I suspect that "how assertive should I be" is the wrong question to ask-- there are many ways of being "assertive", only some of which work well! As a society, we are still in the process of developing-- and raising awareness about-- workable and effective sexual/dating "scripts" that men can stick to, and trust that they won't run into obvious problems. As the article hopefully makes clear, even the outwardly-trivia…
If we develop a set of working scripts to indicate availability, then women will still go for men who are "bold" enough to deviate from the script and seize the day. It's a complex issue, and it's my belief that the traits that women find attractive in men and the traits that women would like to find attractive in men are two different sets with less overlap than you'd imagine.
There will be lots of ways to signal the kind of "boldness" you (and women) want, while still staying well within the 'script'. So hopefully this won't be a big issue in practice. (Though it's hard to say since we don't even have broadly-acknowledged 'scripts' yet!)