Personally I'm relieved that this is a scam. I mean, seriously, one mini rig replaces about 20%-25% of all mining globally?
Your math is bad. It would be only 2% (1.5 Th/s out of 70 Th/s).
And, no, BFL is not a scam (they have a working prototype of their ASICs - not the Mini Rig though).