Of course I can visualize things in my mind. Everyone can. Some people just don't know they can. For some it comes quite easily for others not so much. I've known people that say they don't see anything in their minds. I have a lot of experience with this, teaching it and such.
Some really do see in their minds, but when told to visualize something they think it should be this crystal clear image and because it isn't they say they don't see it. You can actually feel an image or vision just as well as visualize or see one and for some people it's much easier to feel it. It's not important that he see it clearly or at all, but that if he wants to continue this to just go with it and let himself feel it, sense it. I've seen people that say they cannot see anything in their minds and after weeks or months of guided visualizations they will suddenly have a break through and see images.
The first time I heard someone tell me they see nothing I was taken aback for a minute because to me it seemed such an easy thing. I knew not everyone would see things in the exact same way but I thought everyone did. The propensitiy is there for everyone even if a person doesn't know it.
Some people are more audio than visual, some people feel more or just have a knowing. Some people do see in their mind but don't really realize it. It's not a matter of one being strange or not, it's just what it is. All things being equal. He knows what a red apple is, a cloud, and so he's still connecting.
Everything in this world has first been a thought and a visualization before it became manifested as a physical reality.
For me as much as I've worked with spiritual visualization and I'm very good at it, I am more of an audio person and sensing person as to how I recieve knowledge, how I work and always have been.
p.s. my husband and son are engineers and are very good at visualizing and my other son is very science minded and too is very good at visualizing.