Yep, I sort of understand this. My take on this though is that the guy wasn't specifically radicalised. That's not to downplay the fact that this happens, it certainly does, it's just a hunch regarding his background. ISIL claimed this guy was one of their so-called 'soldiers', yet this guy was a bodybuilding sted-head who's had a criminal career spanning 20 years.
He's been charged with public order offences throughout most of his adult life including GBH, yet none of this was ever attributed to ISIS or ISIL, and rightly so, because those groups weren't around during this time.
I tend to think he was known for being a knobhead, and has recently carried out a knobhead fantasy perhaps by being brainwashed online - within quite a short period of time. A knobhead will often be a knobhead, however I do feel that ISIL/ISIS are using this idea of 'one of our soldiers' as nothing more than an opportunist moment. If he was a trained terrorist then his training was a bit shite. Expecting to enter the houses of parliament with two kitchen knives against armed police is about as ludicrous as expecting to meet 72 virgins on the other side.