Sandals do still discriminate. They have recently been prohibited from advertising on public transport in London because of their discriminatory policies.
They don't advertise it heavily, but for example on their UK website the prices page is headlined:
TheCaribbean's no.1 ultra all-inclusive for
mixed sex couples from £899 per person
and
Sandals Resorts - Exclusively for Couples
Choose one of our 12 Sandals Resorts for a romantic, mixed sex couples only holiday.