The Boglodites' inexplicable delay in the altered timeline.

The Boglodites were inexplicably delayed 40 years in the altered timeline, but yet weren't starved to extinction, as per their fate in the original timeline. I can kind of see how it would be too stressful for the time/space continuum to allow them a timely invasion in the 60's, because it would interfere with the circumstances that led to the time jumps that altered the reality in the first place. Kind of the timeline's own version of the Grandfather Conundrum. It seems like that wouldn't apply to very different timelines, and I don't think it does apply to timelines that are far apart, but I feel like it would apply to timelines that are parallel enough for a person to slide directly from one to the other. So, okay, the Boglodites couldn't invade until a point in time after the time jumps occurred. But, those Boglodites should still be starved to extinction, by the time modern time rolled around, as they were in the original timeline. If they survived by consuming something else, what could that something else have been, that wasn't available to them in the original timeline? I liked the little James/Agent J twist, though.