Of course a person can be disabled and still capable of running, but as has been said, there is massive abuse of the blue badge system - it's thought up to half are being wrongly used. For example:
Thiswww.telegraph.co.uk/news/uknews/1990469/Drivers-commit-disabled-parking-fraud.html
or business.timesonline.co.uk/tol/business/industry_sectors/transport/article3241387.ece
In that second link, by the way, it does suggest that to get a blue badge, your disability does have to impair your mobility in some way - so the OP has a point. Quote: 'The rules state that, to qualify, a person must have a ?permanent and substantial disability which causes inability to walk or have considerable difficulty in walking?.'
I'm just reading from the articl, not talking from personal experience - some of you with blue badges will of course know more. But from the OP, if the above is true, it does sound like the driver shouldn't have had a blue badge at all.
I have a condition that makes it advisable for me to use disabled toilets, so I am familiar with the glares you get from people who clearly think you are abusing the system since you are not in a wheelchair, as I leave the toilets. There's no real way to win as I don't want to stop and explain my medical history to them, and shouldn't have to. However, my condition doesn't affect my mobility so I would never apply for a badge and would never park in a disabled space. I don't need them, other people do.