Past events have no freedom, as they are already done.
If you can know future events, those events are also set in stone.
Pretty much. Unless something's arbitrarily altered by the postulated force or forces outside time.
Either way, AvalonXQ is fighting a straw man. It's not that knowledge of events has any effect on Free Will, it's the nature of reality that won't allow them to co-exist. Or, to put it a different way, having Omniscience in no way takes away Free Will. In that case, Free Will simply never existed, just the illusion of it.
ETA:
Just because... This is assuming that the Omniscience is in the same plane-equivalent. When you postulate different dimensions involved, things get more complex. In the end, though, interaction between a plane that allows Free Will and a plane that allows something that can be called Omniscience will end up nullifying one or the other.
ETA again:
The definition of free will is a lack of constraint on my ability to make a decision, not a lack of knowledge as to what the decision will be.
So, the crux of the matter, then, before any argument is presented... Do you consider a physical reality that there was only one path that you ever actually could make to be a valid constraint? What about a physical reality that allowed for more than one potential path, but that did not allow any conscious effect on the forces deciding the path?
Either way, I tend to use, as a rule of thumb for a minimum version of Free Will that is in any way reasonable to use when dealing with a moral Free Will, as is usually the actual issue at hand, "a person must be able to consciously affect which one of multiple potentially selectable options is selected, with at least some knowledge of the consequences and ability to comprehend the consequences that will result, before making a decision."