A gifted V/S learner might prefer drawing geometric shapes out of a personality preference. A similar V/S learner who prefers curved lines instead might be more likely to become the next Rembrandt. Of course, there are situations in which geometric patterns can be quite artistic. He's also still quite young, and preferences can evolve, so in this case, so I wouldn't read much into what he's drawing in particular.
I wouldn't worry about encouraging either math or art, since he'll likely be internally driven to either/both if that's his prerogative. There does seem to be a strong correlation between geometric preference and math interest, so it's highly likely he'll push on in that on his own.
In your place, I'd provide him with the opportunities, and then just follow his lead.
