Technically not true, but also true at the same time. Taking the protein within the 30-45 mins is not going to inject/supercharge your muscles with protein and give you massive gains. The idea is to take advantage of the insulin sensitivity spike and to replenish cards as fast as possible. Avoiding muscle catabolism is always a good idea.
The hard rule is that your pre and post workout meals/shakes should never be separated by more than 3-4 hours. There have been countless studies for and against the anabolic window.
tl;dr: It's not 100% imperative that you consume 400g of protein with 29:59 minutes but it does generally help.