"he’s lying out his ass (way more likely)" Why would he lie? When they don't want to give away spoilers they just say, "I can't say." They don't lie. They've never lied to subvert a plot. They just don't talk about it. Why would you say that Jensen doesn't know how he interprets his own character's thoughts and feelings? I like Destiel as much as the next person, but choosing to ignore literally everybody saying "No, it's not like that" b/c it's not the answer we want is not helping anyone.
(about this)
I’ve wondered that myself, actually. why would the showrunners/Jensen bother telling us Destiel isn’t romantic just to throw us off? it doesn’t make sense. we cry out for people to tell us it’s never going to be canon if it isn’t, and please stop queerbaiting, but then when someone actually says “they’re like brothers” we’re all NO THEY’RE IN LOVE. it’s like we can’t take a hint.
what’s very important to remember is that what Jensen says, and what anyone working on the show says, only matters up to a certain point. what they say, what their individual opinions and interpretations are, it makes as little difference to canon as the input of any fan watching. Jensen is not making the show by himself, he’s just answering questions on stage. the writers make up the canon, but the broader community of creators working on the show all have their own interpretations. there’s dozens (hundreds?) of people making the show as a team, and the final output is an extremely potent romantic storyline between Dean and Cas.
what anyone says at a convention or on twitter does not matter until the show ends and their words are proven true or false by canon. and even then, parts of the narrative can (and will) be left up to your personal interpretation. whether or not Dean sees Cas as a brother is not up to Jensen, it’s up to you.
the canon narrative in the show implies that Dean and Cas’ storyline is romantic. Jensen’s acting with Misha says it’s hella gay. ergo, if you want to believe Destiel is real, then Destiel is real. whether or not they’ll textually cement that in the future is still up in the air. until that point, nobody is going to tell us outright that it’s happening, because that is a massive freaking spoiler.
sidenote: the only way Jensen (or whoever) can avoid being accused of spoiling a Destiel subplot is if he says they’re ~brothers~ because nobody second-guesses that being a brother to Dean = someone he loves/is close to. it’s not new information. it’s a non-answer. personally I choose to believe that the word “brothers” is the nearest Jensen can get to saying “love”. whatever he says, he can’t outright state “Dean loves Cas” the way he can say “Dean loves Sam”, because even though he says the word “brothers” it won’t be interpreted the same way. why is it not the same? because Dean and Cas’ relationship is supposed to be romantic and everyone knows it, even if they don’t ship it. for example, if Jensen said “Dean loves Sam”, do the Destiel shippers freak out that Wincest will go canon? no. but if he said “Dean loves Cas”, all hell breaks loose on the Wincest side of town. Jensen has to be very, very careful what he says. saying they’re like brothers has worked for years to allay the fandom’s questions about Dean and Cas, and that’s how he avoids answering it, just like you said. maybe he does indeed think they’re like brothers. but he’s not going to change tactics now, regardless of whether he actually interprets the relationship that way.