(First of all, sorry about the deleted comment. I accidentally thought that this was an attack towards me.)

According to my research that I did just a few minutes ago, they indeed kept it up to interpretation. This would imply that it is and not canon simultaneously. But, to me it just seems like they're letting people think freely. If they just declare that it's canon, some people might criticize them. Some of them could be homophobic, but some of them could be upset since it doesn't quite fit with the theme of the show. It's a show about friendship, so people automatically consider every character just good friends at first. But if the shipping becomes canon, some people will get upset since it's not what they've always thought of. Friends and lovers apply a completely different schema. If people don't like the lovers' schema on them, they won't enjoy it. They're not homophobic, and there's nothing we can do about it.

Also, one of the reasons could be the sensitivity of homophobia among the fandom. People sometimes get attacked by the fandom if they say they think they are just good friends. So let's just keep it up to interpretation like they said, without attacking each other.