We do know how to inefficiently create and store antimatter, we don’t have any idea how to cause human hibernation.
To me getting two dozen of orders of magnitude better at something is clearly hard, but that still beats trying to do something we don’t have a clue how to start. For human hibernation step 1 is probably serious genetic engineering and there’s going to be other steps.
Hell, we can't even store hydrogen without leakage issues and with anti-hydrogen any leakage is very bad.
World ending doesn't begin to describe what that looks like.
Do the same thing over a year in many different devices and you’re basically dealing with a normal nuclear power plant’s output.
They've put pigs into suspended animation for an hour or two, I'm not sure what the upper bound is on that or how much further it's possible to go with it. Ditto organ deep-cooling. So while it's not feasible now, it feels like we need "only" 100x or so improvement to make it viable.