Why would the address for the NXT genesis block be involved in Asset Exchange NEMstakes manipulation?
It probably has to do with making money

Next question is whether the activity is ethical according to the stated principals of NEM?
Can you elaborate more, otherwise, I suppose you want to get NEM cheaper.
Of course everyone wants something cheaper but I would be happy to share my observations and maybe someone can help me understand a little better if I made some bad assumptions.
I reviewed the orders on the NXE AE and noticed one address repeatedly placing several bid orders interspersed with ask orders and cancellations. Hmmm...looks like a bot to me. So, I investigated the address a little and found that it was the same address as the NXT genesis block: NXT-MRCC-2YLS-8M54-3CMAJ
Well, that was interesting and I wondered if the NXT community would be so overt (and maybe they are) but then I stumbled on interesting news in February when the so called "doctorevil" successfully hacked the passphrase for the genesis account. Clearly, the account could have transferred to different hands at that point.
In any case, someone with strong NXT ties is manipulating NEMstakes on NXT AE Exchange. Algorithmic trading may not be bad in itself but, in this early phase, when the NEM community is trying for a sterling reputation for fair distribution based on principles of equality...it is lack luster to say the least!
You are on the right track but need to do some more reading. Everything happening is legitimate.