You could complain about close source, but let's look at it from a different perspective.
Many Wall Streeters are laughing about open source ICOs. If your business and product is open source software, what value does your project have, they wonder? Anyone can clone it and take your user base.
With that reasoning open source is especially a big risk for ArcBlock because as far as I know there are few programmers on the team. Anyone with a lot of money could copy the idea and code, and put a rockstar coding team on it, for example Facebook.
That's one argument for closed source, protecting intellectual property. Of course it could also be an excuse for not having a lot to show. Being open source hasn't hurt Ethereum really, there is Ethereum Classic but it doesn't have the same level of programmers as the original.
I agree with you if this coin really does deliver what it promises to do (blockchain 3.0) it's worth the risk to not having it open source imho.
But i also know that trust isn't earned easily in the crypto community so i am kind of torn.
The positive (no copy paste coins stealing their maybe world changing idea) outweighs the imho (small) risk of malicious intent.