I wouldn't be surprised. It sometimes takes decades for people to be able to deal with these types of issues. Look at how long it took many of the victims of the pedophile priests to come forward. The other issue that many of these young victims may be dealing with is that Jackson is a man and they may be afraid of coming out as gay, or as being seen as gay. This would be an additional problem or stigma for many of them, especially in the Hispanic culture, which I understand is very conservative in this regard.
You're absolutely on target about victims being afraid to come forward for fear of being branded as gay. I have a friend who is straight who was molested by a child psychiatrist as a kid. The main reason he was afraid to come forward was because he thought people would think he was gay. Luckily he has overcome that. There is going to be a trial against this child psychiatrist in - yikes - California next month. There are six other victims that we know of and once the news starts covering it, we expect many more to come forward.