How is it theft?  That would just demonstrate a display issue and show that the value is actually lower than you are seeing.  It doesn't change the possible idea that what is happening is that you are credited for the mBTC value of the coins when you mine them and then they get converted to the coin of your choice when they mature.  Maybe there should be code to make it more efficient by not exchanging coins and then paying them back, but that doesn't mean it is theft.  It just appears to be inefficient for your purposes.  You may not like the way the pool operates, but it is not doing anything shady that I can see.  It just isn't as straightforward as other pools.  The fact of the matter is that no one is forcing you to use this pool.  If you don't like how it operates then don't use it.  Not to mention the source code is available for your viewing so you can easily confirm how it operates yourself if you really want too.

I would say if you are trying to mine a coin directly without exchanging then there is no point in mining on Zpool.  The fees aren't the lowest out there so why would you be so insistent to mine here knowing that the purpose is to auto-exchange coins for multiple algorithms?