By your definition - it had thousands of downloads and the organisation that produced it has thousands of members who clearly do not find it offensive and that likely extends to tens or hundreds of thousands of evangelicals (if not millions).
That's how subjective works.
Any treatment / cure that is advertised as such (without BIG BOLD letters of warning) should be approved or banned by relevant organizations -- there's precedent for it, like Scientology's E-meters being required to be marked as a "religious device".
By my definition "offensive" is a notion or device that's used to spread hate or shame versus other people's condition, people which are really harmless for society as a whole -- since gayness is not really a disease.
That's contradictory - if it's offensive by definition, there is no room for interpretation by the subject and therefore it can not be subjective.