Poor old Mr Dornan -
The compound word 'homophobia' is of Greek derivation, not Latin and means 'fear of the same'
Which probably doesn't help
This further complicated because it is a synthetic (aren't they all?) word, really contracted from 'homosexual phobia'.
The complication arises because 'Homosexual' is one of those mash ups beloved of 19th and early 20th century 'experts' where we have the Greek 'Homo'=same, and
the Latin 'sexualis' = sex
so 'homosexual' means same sex, (albeit with two distinct language roots) not sex with a man.
Poor benighted colonials.

(I wonder if Mr Johnson paid sufficient attention while beating fags to remember the dual root?)