Rules have no idea what you want. They express what the
foundry wants, which is in this case an explicit ohmic (and
not very many ohms) tie of every electrically distinct "well"
(N or P) to a known signal (usually, but not necessarily, a
supply pin). This is all to prevent the foundry to have to
spend time and effort dealing with customer panics that
have to do with floating FET bodies causing mystery FU.
It's not about what you may want out the the NWell.
It's about making sure that whatever goes on there, is
on purpose.
In the rules logic a same-species contact to the well
(perhaps additionally constrained as to max distance
from active) "stamps" that region and "unstamped" are
declared an error.