Well, yes, IME the primary limiting factor on getting productive work done after work is energy, not time. But the article is about golf, which for many people is a relaxation pursuit akin to TV.
Some of it undoubtedly is, but I suspect that there are a number of people who actually watch 7+ hours of TV per day. Remember that TV watching is concentrated among older people; the average for 18-24 year olds is 2 hours/day, for 65+ year olds, it's 7 hours/day, and even for just 50+ year olds it's > 6 hours/day. [1] "Media multitasking" is concentrated among the young, those < 35 years old, who watch the least TV anyway.
Just thinking back to my childhood in the 80s, I could totally believe this. I'd come home at 3:30, watch the entire Disney Afternoon until 5:00 when my mom would get home, pretend I hadn't been watching anything, then watch the news with her (6:00-6:30), have dinner, and then usually watch an hour or two more of primetime. That's about 4 hours a day, as a 9-year-old.
These were the habits of three whole generations (Silent, Boomers, and Gen-X) and half of another (Millenials). I don't watch any TV now, but that's because computer games and the Internet replaced it in my teenage years.
https://en.wikipedia.org/wiki/Television_consumption