Unity and Unreal are Game Engines, not 3D Software. Yes, It's possible to use U and U for 3D modelling, but nobody with a chopchop brain do it. If you work with U and U you create the model in Blender/What ever and import it to the engines for the programming backend.
I think that's not the point the parent is making: his point is that the difficulty of finding people able to use it (because of the cost of the software) could be solved by either offering a free option, with the example of Unity and Unreal, which both have a free option, so you find a lot of people who have used them.
Unity and Unreal are Game Engines, not 3D Software. Yes, It's possible to use U and U for 3D modelling, but nobody with a chopchop brain do it. If you work with U and U you create the model in Blender/What ever and import it to the engines for the programming backend.