If this was a full technical discussion between p-chemists and engineers instead of a discussion for boat owner folks without the in-depth tech discussions in order to simply relate that water in fuel oil *doesnt have to be problem in fuel tanks* then such 'literary' simplified discussions are indeed appropriate. You want calculations and empirical data with that?

Remove the oil from the tank, for little to no water uptake when storing for long term. Cant make it any simpler than that.