ESA or UC?

Very much hoping that you can assist with some queries I have over a Beneficiary that I am helping with some benefits claim.

He has Muscular Dystrophy and has been working on and off over last few years but is struggling now and his work through an agency has has dried up. We have got him on Universal Credit and have also now tried to get him on ESA with a view to getting him in the support group so he is not hounded to return to work as his condition is worsening. He has been sent a letter stating that he cannot receive ESA as he has not made enough NI contributions in the year April 22 to April 23. He did work for the agency in this year in question and believes he earnt circa £14.5k and was paid through Pertemps recruitment.  

What happens with cases like this? What are his options for benefits if his NI isn't enough for ESA? Would his earnings in this year nit be enough if he only earnt £14.5k?

Be grateful of any advice on which way he should go now.