Sockstar I agree with you on your 4 points and I think a relationship between Sam and Freddie wouldn't make sense at this point in the series (I can't say anything for sure about the future), however I'm just going to play devil's advocate on how Sam loving Freddie could make sense.

Starting at season 1, Sam and Freddie were not friends, Sam teased Freddie all the time and he just gave her more motive to continue by reacting exactly the way she wanted him too, so she had no reason to stop.

Then season 2 came around and Freddie started maturing, he started fighting back, teasing Sam back, getting her back on pranks and not getting so offended by her comments. That impresses Sam, she sees that Freddie isn't just a weak 13 year old that she can pick on and get away with it. Then iKiss comes along, Freddie pranks Sam back for the first time and she gets angry and vows to get even...but she goes too far, and after a brief talk with Carly (who didn't help her at all, she pretty much told her that "you went too far this time, and you can't fix it," now if Sam had just listened to Carly she still may have felt guilty, but she wouldn't have apologized live on the show, nor would she have paused the show to go out to talk to Freddie, because why would she? She had to feel something on her own, not just going by Carly's word to go out there and talk to him. Then the kiss scene, which I'll concede is debatable whether or not the kiss actually meant anything, but the most important part of the scene wasn't the kiss, it was Freddie's line of "I hate you" that he said with a smile, and Sam's chuckle and return of "hate you too," those three words were a huge advancement in their friendship. Then, later in the season Sam comes to Freddie for help to get rid of Missy and he helps her because she was really upset, another showing of how he cares and although I can't assume she found out he did that for her, it would make sense if she did, another advancement in their friendship and Sam continues to see Freddie in this more mature, grown up, caring light.

Then in season 3 in iSpeed Date, when the last scene occurs, there's no doubt she looked hurt. I understand the three possible scenarios it could have been about Gibby, or that her friends weren't there to support her when she needed them, but of course you can't disprove the third theory that she didn't like seeing Freddie dance with Carly because she left without a word and the episode ended. Then in iSYL, she gives Freddie advice because she knows that Carly is not in the right state of mind to date Freddie at the moment in time and she can sense that it could easily end in hurt. Obviously it is much more likely that she is giving advice for the sake of keeping the groups friendship in tact, but that must show that she does care about Freddie's feelings and happiness and doesn't want to see him get hurt.

Now those are the most obvious signs, and things like that don't just go away over the years. I agree season 4 turned away from shipping in general, it was the anti-shipping season (until now) so I can't add anything more and I 100% agree that a relationship between them that starts now in the context of the season would be out of nowhere. However, I can also understand the point of view of the people who think it makes perfect sense for Sam and Freddie to get together. That said, I think no relationship will come out of this episode and instead we'll get a great friendship developing moment, and an open ended ending with a scene we really have to think about. Either that or Brad does accept Sam and he turns into a kind of Pete character.