You could, but then (if you insisted on using different circles to measure circumference and diameter), you'd probably say that the diameter was 9.55 feet and the circumference was 31.4 feet. This is because the inner diameter (what can I fit inside) and the outer circumference (how big is this thing) are far more useful and meaningful measures than the inner circumference and the outer diameter.
But come, these are Clintonian word games to try to rescue the literal truth of that passage. If the Holy Word of God requires Clinton-speak in order to parse it, you know that your approach to it must be wrong.
I don't see it that way. I see that there are in fact two circles that can be measured and need to be described in order for complete information to be delivered. One circle clearly refers to the rim and for that we are given the diameter. I for one would never assume the rim to be the same size as the main body. For example, I have a coke can in front of me with a rim that is smaller than the main body and I have a tea cup where the rim is larger.
The author then gives measurements of the body of the vessel.
Seeing that it was designed and built to begin with and seeing that the author is so specific about his measurments and seeing that this text would have probably been corrected by some monk if it was clearly wrong then I submit it is you who is attempting to skew the plain written text to fit your view.
The difference between the two diameters are not that significant to convey the amount that the vessel could contain. The idea that the instructions for the original design would have focused on the rim makes sense to me. For example, I call in a contractor and tell him I want a hot tub 10 feet from rim to rim and I want the edge to flair out. This makes far more sense to me.
Without that information we wouldn't know the relative size of the rim as compared to the main body.
Making an assumption that the only interpretation is that they misunderstood pi or were even mistaken in the measurements they took in light of the ability to make this vessel in the first place would seem the least likely.