Should note 2 major points:
1. The 3rd episode of Torchwood hasn't been screened yet in the USA (the article is wrong on that point). It gets screened 2 days from now in the US (9 days in the UK).
2. Numerous gay sex scenes have been shown on the BBC, including previous seasons of Torchwood. The BBC (like most western TV outside the US) is MUCH more liberal than US television when it comes to sex and nudity, though more likely to censor violence. The issue here is that Torchwood has been moved to an earlier timeslot than previous seasons. In the past, it has been a 'post-watershed' timeslot show, hence giving it a free reign with sex and nudity. The issue with sex isn't that it involves gay sex (gay characters/sex aren't even vaguely controversial on UK tv), but that it is before the watershed.
Britain basically runs a 2-tier system for tv ratings restrictions. If it is before the watershed timeslot for that day, it has to be family friendly - can still have gay characters and gay sexual innuendo (e.g. during Russel T Davies' stewardship of Doctor Who), but no explicit sexual nudity. If it is after the watershed, you can show pretty much whatever you like. Sometimes you get shows where the watershed falls in the middle, and you get a hilarious mid-show upscaling of sex and nudity
.
The Torchwood issue has nothing to do with any general conservatism on UK TV - it's purely a timeslot issue.
In any event, contrary to what the article says the episode hasn't been screened yet.