That is just sgminer from veox ... nothing special about it ... as a matter of fact, the link you are supplying does not even come with groestl.cl and groestlcoin.cl ... so you can not mine groestlbased coins with it ...
I tried the Sgminer-grs.rar, but nothing weird there either ... getting the exact same hash as I was with dwarfpool miner ... so to conclude, it can't be the coin, otherwise Groestl would be affected too, it is not the miner software, or at least not the ones you are linking to .. that leaves the pools. I however believe ocminer when he says he is not detecting fake shares.. maybe (just maybe, coz I have no proof) people were exploiting some loophole in the pool software, but if they were they aren't at suprnova anymore.

Either way .... there is nothing wrong with the coin, and the sgminers you link to have no special features, hell, the one you link to on github can't even mine groestl... whit that much false information I have to suspect this is just a FUD attempt.