Pragmatism is good. You could even have him wrap the tape and thereby gradually learn both pragmatism and mindfulness that a ferrule needs to be snug. Very few kinds are totally resistant to loosening in some odd circumstance, often a result of the other reality that very few anglers will ever completely avoid a moment of carelessness that results in loose assembly or a gradually loosened ferrule going unnoticed. A habit of routine checking--almost automatically--is the best practice I know, same way you develop a rhythm of glancing in the rearview mirror when driving. I do it every time I reel up to move, change a fly, check a leader, and so on.
Tape ain't bad for a kid !
Unnecessary instead, but a touch more upscale and more likely to require grown-up help in assembling or disassembling the rod--would be vinyl tubing or rubber tubing if you luck into some just the right diameter to stretch well over each section. It can be left in place on the uppermost section. Between a hardware store or vacuum tubing at an autoparts store, easy to get. Clear is commonly available.
Doubt it strengthens anything at all; it definitely restrains the sections from loosening and then being at risk of damage.
One of the most damage prone ferrules ever, as fitted on the first System G graphite blanks and factory rods. These were pretty much not if they would loosen and break, but when. Having repaired one with a conventional metal ferrule,and then a sleeve, I have another one that never did break yet because the tubing restraint I added. I used both as knockabouts for years. When one of my grandsons gets a little older and has learned not to break an entire rod, I'll give it to him and enjoy watching him work that ferrule over.
A snug sleeve of surgical tubing will hold a spigot-ferrule from working loose unnoticed, which can cause any ferrule to fail, but adds little strength as such.