I am on my tractor, if I FEEL I can do it safely then I will.
And our free societies allow us to do this with private equipment - 'doesn't make it a good idea. Yes, I'm critical of this idea, unless the second seat is an approved installation. I say this as a person who approves seat installations in airplanes as a part of my living, and, as a retired volunteer firefighter, I've met several operators (generally parents) who were hysterically emotionally decimated having caused injury/death to a child, doing something they thought was safe, until a moment before it went terribly wrong.
It is a reality that coming onto a public chat group, asking opinions about doing something which others consider potentially dangerous, will attract negative comments. Your tractor has a roll bar excellent! So a person seat belted in has good safety. But, would I, as a person who approves seat installations in airplanes, support the installation of a buddy seat? No, it's just not worth the cost (in any sense - emotional, liability etc.) were someone to be injured. I expect that this is why we don't see factory buddy seats on open North American tractors - it's just not worth the liability.
As a result of the very recent death of a family friend child, involving a tractor snowblower, I have reminded my family that children/grandchildren will not be anywhere near our tractors while in operation. On that sad occasion, we all agreed. When they are ready to drive, they shall learn solo, with some helpful adult hollering from nearby, the way most of us did.