Aiptasia and Majano come in on corals for the most part not rock unless the fresh live rock has been exposed to them. An it is a fact of life the one will always be fighting pest's in a reef tank. Just like gardeners due with weeds in flower beds. One spends tons of money trying to create the natural nature of live rock with Dry rock an you can not do it. I see so much failure from that one factor in post's thru out the forums. If ones bacteria and sponge life is not correct chemistry is the least of ones worries. Once a bacterial cycle is robust enough to process the waste in the aquarium in all forms. Then you can deal with chemistry issues.
I can guarantee you it is actually rather simple to recreate the biology that live rock has with dead rock. Bacteria can also come in on many forms it doesn't only need to come in on rock. But you can choose to have it come in on something you can really pick out things you don't want to introduce. Not have it hide in a crevice of a rock and find it when you actually see it months later. The other benefit to dead rock you can lanthium treat it easily outside of the tank, and remove a large percentage of built up phosphate. Rather than putting a rock that may leach phosphate into your tank.