I think this image makes it difficult for owners to sign him.
I thought Kaepernick not getting signed was b.s., but then I saw the things he has been writing on twitter over the past few months. He said he wouldn't take a knee any longer, but he continued with hateful rhetoric over twitter all spring and summer. He has continued repeatedly calling cops racists, murderers, and slave catchers. On 4th of July, he wrote that celebrating Independence Day was the same as celebrating slavery. He has essentially called both Mike Vick and Ray Lewis, Uncle Toms. The Ravens owner was the only owner talking about considering hiring him, but did openly and honestly talk about the off field issues. Rather than responding in a positive way, Kaepernick's girlfriend, who appears to be his spiritual advisor, tweeted that picture. Who would hire a backup who publicly compares you to a vile slave owner in such a public way?