First, I believe them when they say they didn't steal anything. But second, and more importantly, I find it highly unlikely that even if they technically violated some agreement somewhere that it would play any significant role in the success or failure of Shred Video. I think it's just anti-competitive, greedy, ill-will to not allow former employees to succeed or fail based on how well they execute their new venture. It's a dangerous bullying approach that stifles innovation.
Exactly this in the opposite way too - I don't see how Shred Video could hurt Smule. The way I see it there's no problem with them both coexisting, it's not like it's a tiny market or anything. Just seems so unnecessary on the part of Smule and just seems vindictive and pointless. Smule could just, you know, compete with their products if they felt threatened. Isn't that what a market is?
I was also a huge Smule fan and would recommend their apps to people looking for interesting music making tools. Not anymore. Will be doing quite the opposite actually.