R2R again

Hello

I have today met with a Dutch National who can to the UK in August 1997.  He worked in the UK between 1998 and July 2001 before claiming Incapacity Benefit which he was in receipt of for a long period from July 01 to June 2012. He then had a brief period on ESA (income related) from June 2012 - January 2013 before he went into prison for 3 months.  He tried to claim ESA again since he came out of prison however a decision was made last week that he does not have a R2R.

When looking at grounds for an appeal I wondered whether the client would have a permanent right to reside as someone who has legally resided here for more than 5 years, under Art 16 2004/38 directive.  If periods prior to 2006 are considered then I wondered if he could be considered legally here for the period he was working and then if he has retained worker status by being temporarily unable to work for the period that he was on Incapacity Benefit?

The client has no family members in the UK and is not married or seperated from a UK national.

My concern is that he has been on sickness related benefits since 2001 therefore this may not be considered as temporarily unable to work.

If they do not consider he has a permanent right to reside I am assuming he would not be able to establish a right to reside any other way as he would no longer retain worker status due to his period in prison?

In the meantime I have advised him to claim JSA. 

Any advice on whether I am thinking along the right lines would be gratefully received.