you need to bother about total hash on correct chain, not on forking or some pool-person didn't change wallet.
someone may make his own bugged wallet set parameter as 1000000 block reward and run it with 40Mh hash.
what will you do? will you stop to take some time to think?
sh*t may happen anytime, there is only one thing that can prevent that, having more hash on network..
So the person would have 1 kazillian CGA. A currency not listed on any exchange. Yay, he/she did it, never needs to work again.
Besides that: You need 40 mhs to do this, this cannot be provided by some backyard mining rig.
you're wrong, it can be provided by everyone..
all needed is to hire some rigs for one day at @ 0.0140 Mh/day (price is from betarigs atm)
only 0.5 btc to ruin a promissing coin that has some new parameters in it, not bad.
What can they really do? Double spend CGA? Nobody has bought any yet.