It appears likely that there are generalizations [concerning “neutral agreement”] of the type “if infinitive phrases are are non-prototypical then so are clauses. A hierarchy of these controllers can probably be constructed, starting from the notion of “nouniness” (Ross 1973).
Standardized
IF infinitive phrases are non-prototypical controllers of agreement in gender and number, requiring neutral agreement forms, THEN so are clauses.
See #2006.