Is there a benefit to stocking up on 2km eggs I won't be able to hatch until after the event ends?

Solution 1:

When you say stockpiling 2km eggs during the event, I assume you mean that in the sense that you wouldn't be able to hatch them before the event ends, rather than you are going to purposely not hatch them.

In that sense, yes, you should get as many eggs as possible during this event, regardless of whether or not you'll be able to hatch them today versus a month from now, since eggs are predetermined and the egg pools are all mixed up during this event. A 2km egg with an Aerodactyl obtained during the event will still hatch an Aerodactyl even after the event is over.