Side Step Bolt Query (not usual rivnut question)

I bought some side steps for my facelift freelander in order to access the roofbox for an upcoming camping trip (yes I'm a bit of a short arse at 5' 8). One of the brackets for the steps was knackered with a bit broken off so I had a new one fabricated.

The problem I've got is that in the old bracket the big bolt that attaches the step to the bracket seems to be captive in the bracket itself and I can't get it out (see pics). I started to cut the end off the old bracket to get to it but it's gonna take ages with my trusty dremmel and wondered if there was a simpler way? I can see that the bolt is wider at one end but the hole in the bracket is also bigger at one side so I'm a little puzzled why it won't come out!

Well, if it isn't coming out then there must be some sort of threaded nut inside the bracket, but saying that, what was the opposite side like?

I guess you bought these s/h.

It's ok I sussed it. As usual it took the missus to suggest something. I didn't realise there was a plastic end cap. Took that off and could see how it was held on (see pic).

Mine came with the side steps already fitted and although I have checked the fixings which look nice and solid, I have never trusted them to take my full weight when washing off the roof. (I am about 14 stone - 90kgs)

Be nice to know that they wouldn't buckle under my weight.