CESA includes transitional protection after migration from IB - risks in applying for UC Housing Component?

I have a client who is getting CESA after migration from IB. This includes £78.25 per week transitional protection.

He would be better off under UC for housing component rather than HB as both his current non-dependants would be exempt under UC.

He will not be in a full service area until October but I wanted to check if anyone is aware of any likely risk to his CESA (and particularly the transitional protection) in applying for UC housing component when it comes in?

Thanks