It may well not be that bad, and the sidewall is pretty thick at that point, and like I say they are the the professionals who have seen it up close and I wouldn't blame you for one second taking their opinion over mine.
I stand by what I said though matey, I personally wouldn't feel comfortable driving on that. For general pootling I'm sure it is fine, but when putting real load on it and at the risk of catching it on the same spot again I'd replace it.