I don’t know enough about your new tank and its filtration system to say with any certainty if it might be lacking now that you have omitted the live rock. But if the tank went through a bit of an ammonia/nitrite spike when you added two small clownfish, I suspect it will undergo a similar spike when you add a pair of new seahorses and begin feeding them regularly. Right now your aquarium has probably stabilized at its current carrying capacity of two small Nemos, so adding two seahorses will likely increase the bioload to the point where there are ammonia/nitrite spikes while the aquarium adjusts to its heavier stocking density.
What are you using as your primary means of biological filtration in the new aquarium, Kris? If your setup includes a wet/dry trickle filter, external filter with bio-balls or other similar biological media, sponge filters or so on, then the live rock is a luxury in terms of the filtration it will provide and your aquarium will probably do just fine without it. But if the live rock was an integral component of your system that contributed a significant amount of nitrification and denitrification to your biological filtration, then you’re new tank will have a very limited carrying capacity and very little margin for error. That could spell trouble when you start adding seahorses, with their messy feeding habits.
If you omitted live rock from your new tank for fear that it may contribute to a recurrence of the copepod bloom that caused so much trouble in your previous tank, that was probably an unnecessary precaution, Kris. It’s a good idea to "debug" live rock that’s intended for a seahorse tank in order to rid it of unwanted hitchhikers and pests such as mantis shrimp, predatory crabs, fireworms and Aiptasia rock anemones, but the types of copepods that normally populate live rock are almost always beneficial species that are desirable to have in your tank.
Five to six weeks is normally sufficient time to cycle a new aquarium, Kris, and if you can provide me with a little more information about the filtration system in your new tank, then I can give you a better idea as to whether adding some live rock would be beneficial or whether you are likely to experience an ammonia and/or nitrite spike when you add the new seahorses.
Best wishes with all your fishes, Kris!