As part of TPB accepted operations, it's possible to reserve tables for reading or writing, shared or protected. While it's possible that a user reading a TPB discovers that the same table was used twice with incompatible modes, when views are used, it's unrealistic to expect the user will discover the problem, since a view propagates it's locking types to the base tables and these tables in turn may be views, until the real, base tables have been hit. Since views can share tables or other views and different views in the same query can have different table reservation options, the engine doesn't complain: it simply assigns the latest table reservation it process to a table and overwrites any previous setting for the same table, silently.
This is related to CORE-1600.