Kaep is a slightly better Tebow in that his talent level is probably best suited to back-up and occasional starter in the right system AND in that his talent level isn't worth the distractions brought forth by them being who they are because NFL teams don't tend to like mediocre or sub-mediocre players grabbing attention for non-football related reasons.
Without the protests, Kaep would likely kick around the league for a decade or so, serving as a somewhat competent back-up and short-term starter, but the odds of him ever looking like he did over his one good stretch at the beginning of his career for any actual length of time would be pretty small. It simply comes down to him not being good enough to outweigh the distractions he'd potentially bring.
As for the NFL overall as pertains to this issue, they do what they do best -- shoot themselves in the foot due to an inability to figure anything out (I mean, every year it seems that "what constitutes a catch?" gets more over-complicated). I said this on the pro sports forum before, but only a few players were actively kneeling when Trump had his "fire up the base" comments about firing those sons of bitches, which spiked them to kneel a lot for a few weeks, leading to Pence hilariously and blatantly staging his own reverse-protest. And then it died down and wasn't really an issue throughout the playoffs and with the general environment at the top being "unless you're elite, you might not be employed if you do this because regardless of your intentions, a lot of people are seeing it differently", most players didn't seem likely to continue the protests. And so the NFL owners had a meeting to proclaim rules and bylines as to what they can and cannot do, with the only notable result being to piss off a lot of people, so instead of "If them guys keep disrespectin' muh flag, I ain't watchin'!!!!", it's "If the NFL keeps disrespectin' muh players, I ain't watchin'!!!!" this year.
In short, by making rules about it, the NFL might have appeased one group of idiots, but pissed off another in the process. GOOD JOB!!!!