I don't think it is age discrimination...
Insurance companies 'discriminate' on grounds of gender, house location, parking location and age.. but they say they have the stats to back it up..
Some companies refuse to quote for younger drivers... some may refuse to quote for provisional drivers, some companies I believe refuse to quote if you live in certain estates... (the last one may be an urban myth)
Stats can be used to 'prove' anything... what I mean is that I'd say diferent colour cars have different claim rates, so they could in principle charge different amounts depending on the colour of your car, or your hair, or the type of pet you have...
Can any mathemathicans say if they'd expect any statisically important differences in claim rates depending on things like colour of car, or hair, or type of pet, ... as the insurance companies say there are statisically important differences when it comes to gender or age?...
If so, I think a case could be made that the insurance companies are choosing which criteria they use to discriminate on, and if they chose different criteria then different people would have to pay the higher premiums and other people would have their premiums reduced...