You are mostly correct as far as your points about the SALT limitation, but the payment made on behalf of the individual owner where a composite is not filed does have to opportunity to include the taxes paid in the calculation of itemized deductions vs the standard where it may be possible to gain some benefit if that owner hasn't already exceeded the limit and is itemizing. Also, there are more things consider if you are advising and preparing the S corp returns, and especially if there is more than one owner.
The operation in nonresident states to create a liability isn't an absolute given, but has the *potential* to do so. Filing a composite return may yield a higher tax overall than if filing individually because not all owners may be in the highest bracket in the state, especially if operating in states having graduated rates, and the individual owner may possibly be able to utilize other deductions or exclusions.
Some reasons why filing individually rather than using a composite return may be better:
the individual may be able to have some of that payment refunded that the passthrough made on his/her behalf,
the individual will also be able to claim a credit on the personal resident state return for taxes paid to other states, and
if the individual's return has other items of deductions or losses that factor into AGI, filing individually may yield a lower state tax than the composite return at the highest rate in that state
Not meant to be all-inclusive as I'm sure I missed some points, but here are some other considerations in deciding to file individually:
If the passthrough has more than one owner, composite payments made for only those that are nonresidents may violate the company's operating agreement as to making equal distributions for all if there are owners or partners that are actually residents of some states, so cash payments may be required to some owners to make sure that distributions are equal for all, especially in S corps where unequal distributions are prohibited;
Some owners may have other income from those nonresident states, so the benefit of the composite return is negated or is to the detriment (see the point above about credit for taxes paid to other states);
Owners move, so there may be times when an owner is a part-year resident of two of the states where the company operates;
Owners with potential nexus or domicile issues in a particular state should carefully consider whether or not to file composite returns on his/her behalf because the statute of limitations does not start in that state if no individual return is filed;
Composite filing at the company level does not allow the individual taxpayer to choose between MFJ or MFS, if there may be some benefit to doing so for a particular state.