This is not necessarily a complaint about the reload times (although I do personally think it shouldn't take someone twice as long to replace the ammo in a shuriken catapult as it does an autogun), rather, how would you justify it in game? 10 seconds to reload a lascannon sounds reasonable, but what are you doing in the 10 seconds it takes to reload a catapult (or pistol for that matter, same length of time for both)?
There are two ideas I've been toying with. The first is that, going from the artwork in the Creatures Anathema, these reload times are for the old fashioned 2nd ed discus magazine catapults, rather than the newer stick magazine catapults. This would make sense as the discus looks like it is far more complicated to fit into the gun than simply sticking another stick into the gun (which visually at least looks exactly the same as replacing a lascell or an autogun magazine).
The second idea was that the reload time was for a human, with eldar being able to reload faster (as the gun is psychoconductive it should come apart at a thought, without requiring the use of hands). Considering the oldest background for eldar weapons actually used a mind impulse to fire them, they didn't use triggers it would make it impossible for a human to use an eldar weapon unless they were psychic.
My biggest problem is trying to figure out how a weapon with a magazine that fits into the bottom of the gun in the same manner as an autogun takes twice as long to reload.
Hellebore