Good points. Almost convincing! 
But arguing with cousin who he has lots of rivalry with and who he is not used to being able to win against him, ever? Context on that point too.
Hearsay evidence level. Supportive of the case. But not “canon” level.
Well, if we’re saying we can’t accept hearsay as evidence, I think it’s safe to assume that nearly all MCU characters are virgins.
Interesting way to put it in a show with a lawyer protagonist 
I think the Cap/Virgin dialog was just supposed to show that Bruce and Jen are as much Marvel fan nerds as the viewers.
Maybe that whole line of dialogue is intended to be fourth-wall breaking?
Which brings up an interesting question: is dialogue that’s spoken directly through the fourth wall to the audience canon? Or is it more of an editorial comment made by the character?
I’ll grant a creator saying so gives something canon status.
I’m curious how you came up with this idea. He’s a very trustworthy and principled man, but never lying?
“Hail Hydra” - more misdirection since he didn’t actually say he was a member, but he did say that the Secretary had asked him to take the Scepter - which is an out and out lie.
Why? Tomorrow they will change their minds? Canon is something only to be disputed; never to be settled.
Agreed. Authors get the first say, but not the last.
I would bet that Steve Rodgers said he slept with a USO girl just to get the guys off his back. It would be super easy, hardly an inconvenience.
Poor, innocent Steve Rogers would be easy prey for those USO girls with their womanly wiles. He’s lucky he didn’t get trapped into a shotgun marriage.
Let me elaborate:
Before the experiment, he was a nerd. A geek. An incel. He spent his adolescence listening to the “let’s be friends” speech.
After the experiment, he was tall, strong, and handsome. Women who had been way out of his league, now found him desirable.
I don’t care how smitten he was with Agent Carter. There’s no way he would stay a virgin.
Know what would also have been super easy for him? Sleeping with a USO girl.
Or four. Super-soldier, remember? 
Not for Steve Rodgers it wouldn’t. He is the one person you can count on to always do what’s right. The whole basis of Steve’s personality is always walking the honorable path. Sex before marriage would be out of character. Just my opinion of course.
One thing people always forget about Steve Rogers is that he may be from the 1940s, but he’s from Brooklyn, not Kansas. He went on dates. He hung out with Bucky, who definitely didn’t wait for marriage. We shouldn’t ascribe Victorian (or Evangelical) mores to a New Yorker who grew up in the Jazz Age .
And they’ve been on double dates too. When he’s on the date with the one girl in First Avenger, he’s actually doing a pretty good job until he decides to go enlist for the umpteenth time.
Also, my number one piece of evidence is in First Avenger when Natalie Dormer jumps him, if they wanted to play him as a virgin, they would’ve done the silly “I’m inexperienced and pulling away and waving my arms in the air” action. Instead he full on makes out with her.
On top of that, Steve was a New Deal Democrat. People assume, “He’s old, so he’s probably pretty conservative,” but politically, he’d be a little to the left of Bernie Sanders.
There’s nothing dishonorable about pre-martial sex, but there is a little bit of dishonor in misrepresenting yourself to win the approval of your peers.