New Style JSA - but should have been New Style ESA?

Hi
Met with someone today, always worked, and was made redundant.
Looked online, applied for New Style JSA - despite having a medical condition that limits their ability to work, this was disclosed in the original application for NSJSA.
Fast forward 6 months - no longer eligible despite having submitted fit notes to DWP.
No option to claim UC as no housing costs and has a private pension equating to £400.00 p/mnth.
My thoughts are that he should have instead applied for NS ESA, he wasn't aware of this and said that "back in his day it was JSA" so that's the route he persued.
Do I have any grounds to appeal this? Surely the WC should have moved him over from JSA to ESA when he began submitting the fit notes? He submitted over 3 months' worth; had he been on NS ESA or even UC, this would have triggered a WCA, but not in this case.
He should, in theory, be eligible for NS ESA. Can I do a MR regarding this? If so who do I direct the MR too? Its the rules not a decision made by a DM! But I do feel that the WC should have moved him over? Is it possible to do this? If so can anyone direct me to the relevant case law etc?
I feel he's been badly let down and now will only receive his £400.00 from his private pension.
He's 57, he lives at home with mum and helps her a lot - she isn't in receipt of a qualifying benefit for Carers Allowance, and when I suggested AA, he seemed a bit reluctant, plus that will take time and in the interim he still isn't getting what he should be entitled too in his own right? His pension equates to £92.00 a week so there will be some deductions as its over the £85.00 threshold but its only a small amount so still worth applying if we can.
Any thoughts would be welcomed!