Yes, informed investors here know that ISX operates in a different space to Paypal and Stripe. They only came up because it was mentioned in the mailout that "we, alongside Paypal and Stripe, appear to be in the select few EU payment companies that have now announced an alternative means to comply with PSD2 SCA for cards."
We know which sectors they are going to operate in. We know that some of these areas lay beyond the risk tolerance of entities such as NAB. This is kind of the point of the systems they have built.
Most long term holders would have looked into JK's history as they should with any company they invest in. As @ben79 said, you have provided an article in which a magistrate found in favour of JK (although they did stick him with the phone bill!)
As for his name, I can't speak to why he uses John informally but you will find he still uses his full name on the ISX company reports.
ISX Price at posting:
$1.14 Sentiment: Hold Disclosure: Held