A two year old absolutely needs to nap. My 3.5 year old still naps every second day, and he was one of those kids who had all but stopped napping at 2 as well. It's probably phase, so you should keep the nap routine the same.

I'd tell mom that you don't require them to sleep (not like you could force them to anyway), but you give them the opportunity. A child who falls asleep during the day needs sleep.

Having said that,I give my older non-nappers or inconsistent nappers those tag readers from leapfrog. It's a little pen-type thing that reads the book when you touch it on a page. I find them stimulating enough that they hold their attention better than just books, but they aren't like a screen toy that is going to keep them up if they need sleep. They aren't super cheap (because you need the pen, plus any books you want), but superstore had them on sake for 1/2 price recently.