The correct compromise would be "500km diameter, about the size of Ohio"

This is moderately misleading in some ways, but illustrative enough and also technically valid if somebody wants to model it accurately.

> This is moderately misleading in some ways

I think that this is more than moderately misleading, because it is ambiguous:

- if they meant "diameter is similar to Ohio dimensions", they are a little bit off, because Ohio is about 355*355 km and Enceladus diameter is around 500km

- if they meant surface area, then they are very off, because Ohio is 116,096 km^2 while Enceladus is about 800,000 km^2. In this case it would be more accurate to say that it is bigger then Texas, but smaller than Alaska (if we want to use US states for comparison)