From: Incurable
It's really not that hard to understand why people would be so cautious when it comes to using the Orion client. Regardless of Jagex announcing that the client is legal to use, Jacmob is the ex-creator of RsBuddy (massive RuneScape bot client), and Orion's creator Gh0sT is an "ex-"hacker (there's absolutely no such thing) responsible for the largest known account hacking spree in RuneScape history, speculated (and claimed) to have made over $1m USD from selling the wealth that he stole. Now, whether he really did make that much money from the hacking is irrelevant (mentioned it for emphasis), but it's an indisputable fact that he and his group were responsible, and that it took place.
So, with that being said, is it still really that hard to believe that the infamous RuneScape hacker who created the client couldn't one day decide to just, you know, hack everyone again for shits and giggles? Just because his now-Jagex-employee-buddy gives the client the thumbs up, doesn't mean that he can't change his mind.
Firstly, Jacmob, Speed and another Jagex employee checks over the code changes on every new client push.
Secondly, Matt is contracted, he'd be sued if he did that for very penny he owns.
Thirdly, Matt was given the exploit to hack RSBot. He's not a very good "hacker".
My last point, why would Matt do that? He's making around £17k per month. (Also the $1m is just a lie on the wiki)