This is true - he wouldn't. This hoax isn't indicative of him being gay. It's a far-fetched theory, even if it is the first one that came to mind.
It is far-fetched. So is every possible angle. From what I've seen, there are three dominant theories:
1. He was conned.
Flaw: For three years? When he's on record claiming they'd met in person? And even if he'd lied about that out of embarrassment, you have heard of skype, yes?
2. Publicity.
Flaw: You fake date someone for three years so you can have her die at the right moment to garner you sympathy Heisman votes?
3. He's gay.
Flaw: Setting up a massive web of lies and then killing her (thus garnering more attention) rather than simply breaking up is illogical.
To me, #3 seems least far fetched, but this could certainly get very messy. That statement he put out today is going to get shredded.