holiness: the state of being holy "a life of holiness and total devotion to God"
Describing relationships based on actions which are contrary to the precepts of natural law (of which God is the Author) as "marked by holiness" is deceitful and wicked. The surest way to encourage those living "disordered lives" to continue on that sinful path is to deceive them into believing there are "elements of sanctity" within relationships based on sinful acts. Such deception is the antithesis of charity.
The relationship really is only disordered if they engage in sex. Sex is not the best basis for any relationship. I get that this society is so sex blind that they just can’t get their heads around this point.