A few comments, First, I might be misunderstanding two separate lines here but, MANDATORY SERVICE, in the context of "Starship Troopers" service was only MANDATORY if you wished to become a full citizen and vote, if not you could skip it, as apparently many did, and remain a non voting "taxpayer".
Universal conscription of all able bodied Males. was pretty much universal in Europe prior to 1914, when a young man hit a certain age (18-21 depending on country) he served roughly 2 years (again it varied by country) then remained in the reserves for several years. This was how the European nations were able to field armies of well over 1 million troops in less than a month, (Aug 1914) While it was the Rail system that actually put them on their nations borders, it was conscription and the reserve system that supplied the numbers of trained and equipped troops.
"If we are ever attacked by big drooling bugs, spitting acid based saliva and space Herpes, than we can call the "Starship Troopers", otherwise leave it alone and let the Army, Navy, Marines, Air Force and the Coasties do what they do best!"
If you read the book carefully the "Starship Troopers " were the space going Marines, that's why they were transported by the "Space Navy", at one point there is a "historical" reference to the "Wet Navy".
"If he abandons the military as Clinton did, he will never see another term!"
I don't know why that would make any difference, people had the example of carter's abuse of the military and still elected Clinton, for that matter, they had the examples of our lack of preparedness prior to the Spanish American war, WWI, WWII, and Korea, but they still elect a$$holes who want to cut defense spending.