It's worth looking in to John of course, even if only to determine that he is not your George. The place of birth seems a very big error, but then again it was probably not George himself who was giving the information. In my own genealogical research I have found a George registered as Gordon and that was in the second half of the 20th century and he was still alive. So weird things do happen when people other than the person concerned write down their details.
Even something as simple as the census clerk copying the inmates' details and skipping a line can throw off an entire area of research!
There is an organisation dedicated to workhouse history, they also cover the Midleton workhouse
. It appears to have been a very progressive place, with a Turkish bath to ensure cleanliness amongst the inmates.
I do think that the Cork archives are probably your best place to research, and the Workhouse history site may have specialised resources that can be of help to you. George may well have lost his health to the extent that working was no longer possible at all and at 56-odd years old he may have either ended his days in the Workhouse (depending how bad his "sore leg" was), or he may be in the discharge records if he was ever deemed well enough to go out on his own.
One of the things you may also want to look into, although it doesn't bear thinking about of course, is paupers' graves records. One other place that may be of help is the Historic Graves
Hopefully you'll find a workable link to your George soon!