Oh, dear, wrong again, David, but not a bad try.
It works like this:
I'd have to pay tax/NI on any income from any source so, financially, it makes more sense for me to just carry on working at my normal job and my normal rate. I don't have to pay for ink, postage, paper, external drives, travel or any of the other costs associated with the case review because I wouldn't have the time to do it. So then, I'd just keep the money I earn for myself and, if I've got some time after work or at the "weekend" (my working week is Saturday to Wednesday), I can so some bits and pieces on the case, but it would miss a significant deadline and a potentially good chance of moving the case forward.
OR
I can work half my normal hours at my normal rate and the other half at the reduced rate. All of the money would still be taxable, but now I'm also offering to cover ink, postage, paper, external drives, travel, etc, etc out of my own pocket on a reduced income.
Why would I do that? Because I think this is one of the most important developments in Luke's case and if I don't do it, he might miss out on the chance of moving the case forward significantly. Why does that matter enough to me to reduce my own income for that period? Because I care, passionately, about justice.
It's not something I expect you to understand, but my explanation's here for all to see.