I agree with this take. Fairfax is trading at 1.0 P/B while MKL and BRK are at ~1.5 P/B. By itself, the $1B increase in bond income (i.e. from $500M to $1.5B) accounts for a 6% return on book. The one counter to do this is that it may indeed be temporary, although I'm sure they will manage to extend/lock in this income stream for as long as possible.
It's hard to think of another company that benefits from rate increases as much as Fairfax. Psychologically, I think that Prem has to be equal parts excited and cautious. The only thing he wants more than fully capitalizing on the opportunity in front of Fairfax is not repeating the mistakes of the past. Once you've been through a long period of underperformance, it's hard for that not to leave an imprint on your psychology.