If I were an interim manager, I would think that my goal would be to try and make the best impression I could in my short period of time at the helm of the team to try and convince the front office that I deserved the job full-time. One of the requirements for that would seem to be making a good impression on the players. Jim Riggleman, who has much more extensive experience as an interim manager than I do, apparently thinks that's hogwash. When asked about resting players down the stretch, Riggleman gave a long, rambling answer that's aptly summed up by this sentence: "It's a baseball game; it's not a physically taxing sport." Now, I'm not going to get into the debate that I repeatedly do with my non-baseball fan friends here. Baseball is certainly not as physically demanding as hockey or basketball or football. But it's weird to hear a manager say that it's not "physically taxing" in what seems like a derogatory manner.
It's also not exactly crazy to think that most baseball players do get fatigued and dinged up from time to time. Swinging a bat once isn't hard, but doing it a dozen times or more and then doing that every day for six months can certainly lead to some fatigue and some dings that might be helped by a day off here or there. Baseball's not intensely difficult, but to say that players should be "ashamed of themselves" for getting physically tired from playing baseball seems more than a little overboard and I imagine it's a sentiment that won't sit well with a lot of players.
In the end it probably doesn't matter; with Mike Rizzo now installed as the full-time general manager, he'll likely want to put his own manager in place when the season ends anyway. Riggleman certainly hasn't done much to distance himself from the competition either; the Nats are 21-31 since he took over from Manny Acta. That's a vast improvement over Acta's 26-61 record this year, but it doesn't really make it good, either.
