Welfare to Work beneficiary or not ?

Is this person covered by the 104 week linking provision as a welfare to work beneficiary under reg 13A SS(IfW)(Gen)Regs

Single claimant left long term IB 18 months ago to start a job and properly notified DWP (no PCA failure was involved). He worked for a bit then claimed JSA. He was on income-based JSA then fell ill again. Can he now get back to IB under the 104 week linking rule? I’d be very pleasantly surprised if he can!

I’ve looked at reg 13A and Bonner p.796 and nothing there seems to say he can’t. But Disability Rights Handbook p.91 states ‘for income-based JSA claimants to benefit from this linking rule, it must be the claimant’s partner who meets the above conditions’.