If a thread was started 'Does Tom Daley have a girlfriend' and my first response was 'No, I think he's gay', which element of that do you all honestly think would have attracted the most criticism and responses?
Ask yourself this question honestly and if you respond with 'We all would have been outraged that someone suggested he was straight' - go look up the definition of the word honest.
It's not a surprise it's a reality of society that these issues are 'dealt with' like this. It isn't intended homophobia but if you notice this reality, it's hard not to suspect there are undertones of it. Perhaps not intentionally but there is a marked difference in how we are permitted to utilise homosexuality and heterosexuality these scenarios.
'Is he gay?' is always considered far more taboo and unworthy of public discussion than 'Is he straight?'
It's just a British thing, I think, not to want to know about people's private lives. It's the same reason why people who speculate on the wealth of others are seen as vulgar.