I don't think he lies about how much he reads. However I think he skim reads to get through things quickly and that's why he isn't able to form any vaguely complex thoughts on the books.
If it's one of your primary hobbies it's really not that tricky to read 100 books a year. Say you read 100 pages a day, about a page a minute, that's about 1.5-2 hours, so read on your lunch break and before you go to sleep. An average book length of 365 pages will give you 100 books. It doesn't seem ridiculous, and that's before you might add in something like audio books on your commute.
I think the problem comes from not giving yourself the breathing space and time to think about the book. He may read the words on the page and then just move on to the next rather than thinking about his opinions and the reasons behind them. It's fine to do that it you're a casual reader, but making a career off of it you need to be able to form those opinions.