Eh, I don't think 2.5 is too late but I'm not sure I agree with the philosophy, mostly because I think a huge percentage of kids wouldn't agree to being ready at that age. Or any age. Potty training is hard for kids, and most will resist to some degree, so the parent really needs to gauge their child's readiness and appropriate timing.

My mom tried to potty train our child when she was a little under 1.5 yrs (against my wishes, we were on a business trip and Grandma decided she knew best) and it was a total mess. I got fed up and put her back in diapers until 2 years old. It seemed to be the perfect age for her because she did great. So 2.5 doesn't seem wild to me, although it is getting towards the later end of the usually suggested window for potty training.