To the OP- I've always felt that anything the player hasn't detailed and had dm-approved before play is fair game. In fact, last session the party met one of the pcs' brother (whom they had not known existed) and father (who the player had written into his background). They immediately were suspicious of the brother (just because he was named Ishmael and there was water involved), but whatever.
The dm controls the world outside of your pcs, and that includes the rest of the people they know. I have pulled "Surprise! You're not the race you thought you were!" tricks on a pc in the past ("Hm, thought I was an elf, but I guess I am a tiefling"), and not only did the pc love it, that campaign element (the Ilmixie family line) has become an enduring one that has far outlasted the character himself.
It seems that people here have misunderstood what I said. I did not insist in the sense that I shoved my homebrews in his face. I discussed the homebrews OUTSIDE the game sessions, and tried to be as reasonable as possible while doing so. He himself never made it clear if he would allow them or not until the last second, frustrating me a great deal.
The DM's obligation to a good game far outweighs any consideration he owes homebrewed elements that his players bring to him. You may think they were perfectly balanced, but unless you have playtested them extensively and with many different groups, that's a pretty bold assertion to make. Heck, many published rules, written by professional game designers, going through playtesting and editing cycles, etc., end up proving unbalanced over time. As a dm, I have had many players bring their homebrewed stuff to me, and there are almost always issues that I spot that they hadn't considered previously. Consider that your homebrews might have been rejected because of something like this.
OTOH, maybe the dm was just a control freak. That's a bummer, but it's still the dm's call, not a player's, what rules the game runs under. If you really want to use your homebrewed stuff, you should run a game with it and see how people respond. This whole "The DM is obligated to use my homebrews" idea is totally out of line, though; the DM is obligated to
weed out bad rules, and homebrews are a lot of hassle to wade through and audit for brokenness. Long and short, I won't let player-written homebrews into my game without a long hard look, and my time is usually better spent elsewhere.