To me, this image relates to sex panic because often times the people perform sex acts that fall outside of the “Charmed Circle” are often villainized for being ‘deviants’. To those inside that circle, these people represent something they cannot understand; and fear is a common response to things people do not understand.
Asexuality complicates the message a bit because there is a lack of sex acts being performed, but even that falls outside of this “Charmed Circle”. If it is ‘unsavory’ sex acts that are deemed as ‘unnatural’ or ‘deviant’, then a lack of sex acts should not illicit a similar reaction. However, that is not the reaction to asexuality that we see.