Re: If he had been in the UK
They would not have had the right to sack him as he was not in work due to his disability, which cannot be counted as sickness.
Good job you arent practicing as an employment lawyer.
Reading TFA it said "When I returned to work I was informed that I will not pass the probation time and that I am fired immediately,". He wasnt sacked for sickness he simply wasnt retained during probation. In the UK this can happen at any point within the first two years of "employment" and most of the time the employer doesn't need a reason and the employee has no right to a tribunal.
The Equality Act 2010 (which I assume you mean rather than DDA 1995) doesn't give protection here.