I do wonder about this, his sexuality (or other people's perception of it) shouldn't be relevant in this day & age, but at the same time I don't think it can be totally dismissed
After 3 years living/working/socialising so far away from his family, I think it's possible they may not know all the ins & outs of his lifestyle & habits
I can recall growing up through the 70's & 80's when "only a certain type of man wore a pink shirt" according to my elders
Also it's not advertised in the mainstream but not exactly secret what some people get up to over Barton Mills at night,meeting up in the forest/picnic site,many of these could be described as "in the closet".
The road which starts at the waste site/ council depot nearby has become a 2 mile cul-de-sac since the A11 was dualled 2years ago, but is maintained for access to some kind of water company plant or pumping station
I was living/ working close by when a murder happened around the area in the 90's
As far as my everyday life is concerned, I don't care at all what someone's sexual orientation is as long as it's legal and consenting adults involved. If a couple are happy together, then I don't care what their genders are.
But this is a missing person inquiry. Sexual orientation goes toward victimology. It might affect the missing person's behaviour. It might come into it the other side as we're looking at a potential perp's perception of the missing person and what the perp is looking for in this situation and what they feel when they look at the missing individual, which might be a 'signal' that's only in the perp's mind and that the missing person is not purposely trying to send out.
Let's say Corrie is purely straight. A car approaches him and the driver says, "hey, pretty boy, want to come down to Barton Mills with me <wink wink>"? Corrie says "Nope, I'm not that way inclined."
Let's say Corrie is in the closet. His reaction could then be completely different. He's just been out for the night, watching his mates and their girlfriends or mates getting lucky. He feels like the odd one out. So if he gets a drive-by offer, then he's not going to worry about his appearance, not the same way as going out for a pre-arranged date, he's had too much to drink, inhibitions are looser, and he's being picked up so his appearance doesn't matter so much, besides he went out looking 'nice' with his good shirt on and his hair combed, so he thinks "why not?"
Then we have the perp's perceptions and desires. Corrie's sexuality doesn't have to match the perp's want list other than in appearance. If the perp is on the lookout for a blonde, fit, 'pretty boy', then just seeing Corrie walking down the street alone late at night could make something 'click' in this perp's brain, and they're not too obvious when they offer him a lift, because they don't want to scare him away...but there's only one thing in the back of the perp's mind. Being inebriated and not personally caring about anyone's sexual orientation, Corrie isn't enough on the lookout for signs of something being wrong when our perp, driving along, conversationally asks "what are you doing alone at this time on a Friday night, had a fight with your girlfriend?" And the perp, if he's fixated on a goal where he's willing to use force, doesn't even care how wiling the person is, he's become fixated on this person and on his goal, so even if there's no chance of willing participation, our perp is determined to get what he wants.