It depends on how you're defining moral, because for most of the 20th Century, homosexuality (and sodomy in particular) were classed as immoral acts by the general public. Until 1973, homosexuality was officially listed as a mental illness. Steve originates well before the changes in public & federal opinions, and keep in mind, there are still states which outlaw sodomy.

I think one can argue Steve as having prejudices to overcome in that regard, if not regarding the act itself, regarding the place of that act within society - it's all in how it's written, and dealt with in the context of any given story. Steve is human, despite the Super Soldier Serum, and while he may be damn near perfect in a lot of ways, he's still prone to human weaknesses. Steve has issues with Pride, he has issues with Compromise, and he's going to have ingrained beliefs which aren't rational - that tends to be the nature of prejudices. They might be a result of something he saw (or was told) as a child and misinterpreted, they might be the result of specific cultural influences (Irish Catholic family, anyone?), he might even rationalize in the regard that others can do what they want with their lives, but he would never go there himself. Or, he could have an aversion to a personal same-sex relationship simply b/c of how aware he is of the way others view him, and considering maintaining certain appearances to be a part of propagating the values he's sworn to uphold.

I'm not saying that Steve is any of the things above, but the point is, he could be. Even with all of the canon that we have, there are huge portions of his life which are still very much a mystery, and a lot of them are the periods which could greatly influence even subconscious perceptions.

Also, I'm pretty sure you mean "emphasized", not "empathized".