It's generally accepted that males tend to have a more negative attitude toward homosexuality than females:
Three studies conducted with students at six different universities revealed a consistent tendency for heterosexual males to express more hostile attitudes than heterosexual females, especially toward gay men. (Herek 1998)
Men were more negative than women toward homosexual persons and homosexual behavior, but the sexes viewed gay civil rights similarly. Men's attitudes toward homosexual persons were particularly negative when the person being rated was a gay man or of unspecified sex. (Kite, Whitley Jr. 2009)
There's research into finding explanations as to why there is this distinction (e.g. Whitley Jr. 2001), but it does not seem to cover my specific question:
Q: Are heterosexual males more likely to view homosexuality as a mental illness (or as some kind of a "sickness") than heterosexual females?
The homophobia scales I've looked at (Szymanski and Chung 2008, Wright Jr., Adams, Bernat 1999, Raja, Stokes 1998, and Bouton et al. 1987) don't ask questions about whether or not homosexuality is considered a mental illness, but do ask if it's considered a "sin" or "disgusting".