Great route! Maybe it isn't necessary in temperate climates, but the most important point is that he has showers at work. In tropical countries it is a must. If more workplaces had showers a lot more people would cycle to work.
I would say it's necessary in all climates - in colder climates you wrap up warmer, which means the same amount of sweat. On shower availability - all the companies (big and small) that I've worked for in Glasgow and London have had showers and cycle parking.
I live in Chicago (so freezing and very hot at times in the year) ride 11 miles (~18km) each way, almost every day. I keep a pair of shoes, and a towel at work. I take a shower before I leave in the morning, and put deodorant on when I get to work. I rarely need the towel unless it's very hot in the summer. I have a space over a heater I dry out my clothes away from other people. (If anything, having a place to store bike clothes is more important than a shower IMO). I considered that I might be immune to my own smell, but I've had people ask me things like "How come you don't smell bad after riding" and honest friends I've asked and been told no. (The same friends that will happily tell me my outfits look ridiculous)