The IMP doesn't make any sense. If he's mass-dilating due to relativistic effects, he should be time dilating too, in which case he'd never connect because time is passing more quickly for is target. Heck, he'd either be smashed or left behind by the Earth moving through his orbit if he was experiencing that much relativistic dilation. His own gravity would also start to begin to attract surrounding matter.
The Speed Force is essentially magic. When they try to pretend there's anything relativistic about it, they get into trouble.