EmuNAND uses WiFi info from sysNAND and vice versa. You can't stop sysNAND from downloading updates that way :-p (although I heard filling up sysNAND's connections with junk data can stop it from using emuNAND's valid connections).
Actually for the average user it is better - the more average or noob you are the more likely you are to do something to screw up your menuhax system. So better to have an 1% chance of a brick the single time you install it (I don't think it's even that high) than a 0.005% chance of screwing things up every time you use it.
Think of it this way. Would you rather:
1. Roll a 6-sided die once, where if it lands on 6 you get your head cut off, or,
2. Roll a 20-sided die every morning when you wake up, and if it lands on 20 you get your head cut off.
And this is even assuming you are more likely to brick on a9lh installation than screw up your menuhax console, which I don't think is true.
It's not the single occasion of making a mistake that is important here, it's the fact that you have the opportunity to do it constantly for ever and ever instead of just once.
Even if you're super careful and are pretty sure on any particular occasion you won't screw it up - you still have to go through that chance regularly. And if you're a super careful sort of person then the chance of bricking on a9lh installation due to use error goes down significantly also.