Depending on the OP's risk tolerance, he might simply leave it alone and ride. This is what I'd likely do if it were mine. Take a close photo up showing the paint's crack pattern, or mark a few small dots along (not over) all existing cracks, to document the status quo. Then periodically recheck for changes.

There are also various stress indicating coatings that either change color or show obvious cracks at specific stress thresholds. The drawback is that one has to know the stress level target.

Understand that the decision also depends on the circumstances. For example, while I wouldn't buy it, I might build it up if I already had components, and would more likely keep riding it if it were already a favorite ride.

So, engineering and structural considerations aside, it boils down to a judgement call.