That's a good point.
No disrespect to your Dad, but can't he sit in an area where people don't stand? The family enclosure, or the some of the quieter parts of the grounds? If not, whilst I don't want to sound harsh, then maybe he's right to knock it on the head, rather than expect everyone else's enjoyment to be curtailed.
The trouble is that people's understandings and expectations about football have changed: when it became trendy in the 90s, there was an influx of people who had no roots in football, and expected it to be more like other forms of entertainment (the cinema has already been mentioned). And, of course, because they are wealthy, clubs pitched for their business, to the detriment of football's traditional fanbase. Clearly there will always be a small number of traditional supporters who are unable to stand (the elderly and infirm, for example), and they should be provided for, but the rest of us shouldn't be punished because the prawn sandwich brigade can't be arsed to stand up!