Bullshit.  I trade BTC with anyone - except cops trying to do a sting.  There is nothing preventing my 5 year old from owning, buying or selling BTC.  In fact I gave her a few physical BTC for her allowance when they were about $5 and, wisely, she put them in her savings and has held on to them and still has them.

We have taught her to split her allowance into three parts:  savings, spending and sharing.  On her own she decided to do 25% sharing (donations to the things she believes in), 25% spending (candy, barbies, etc.) and 50% savings (she says "for college").