HB stopping when reaches SRP age?

I have a mixed age couple, one is 65 and his wife is 63. They get about 2 quid a week income support and full HB
His private pension goes up by 5 quid a week april, so IS will stop. Ive advised they live off his pensions and her CA, as income is above applicable, but stay on HB as disability premiums are in HB award, and wont be in a UC award.
Client adamant that for HB purposes they are no longer a working age couple when he gets srp in October, so applicable will be £270.
ive advised the law has changed, and they will be treated as a working age couple until she gets her pension in 3 years.
CPAG state’s the HB will stop anyway when he gets his SRP?? A UC claim is recommended?
They wont get any personal living allowance on UC due to joint income, as disability premium isn’t in UC (but inc in HB award) so I have advised against claiming UC for housing costs right now.
Can someone confirm that HB will terminate in October, and their applicable will still be working age at that point due to mixed age rules?? No SDPs in place.
thanks

Sadly I think you’re right on this one - the IS award would stop anyway once he hits SPA regardless and the HB award also terminates due to article 6 of CO31.

What disability benefit is your client entitled to? If it’s ERDL PIP, then he should be passported to LCWRA element with UC once he reaches SPA.