If you think that implies legitimacy, you're wrong. For example, nobody sued Steorn and they ripped off more than 20 million Euros over ten years from hapless investors. Most scams end in a whimper. The victims/marks are too embarrassed to sue and there is usually no money to recover because the scammers have already spent it. Steorn just went belly up bankrupt and so far, no lawsuits. Defkalion vanished altogether and no suits.
With Rossi you get dodgy business associates passing around fake business cards and phantom companies with no discernable business model. With Steorn you get bar-girls. With Mills you get dozens of real-life non-anonymous experts. These experts bring with them verifiable backgrounds with decades of experience working at top tier research labs and R&D companies. The investors and board members are from premium VCs, law firms and industrial companies who have collectively ponied up over $120m and waited with extreme patience for Mills to do his thing. If Mills wasn't on the level, you can believe these folks have the resources and know-how to put an end to it.