I think it is wrong to change the meaning of use base ... for your module. If the behavior of use base is not what you expect, put a note into the docs of your module. That does not confuse users that expect, that use base does not influence the callers namespace. The docs for use base say

Roughly similar in effect to

           package Baz;
           BEGIN {
               require Foo;
               require Bar;
               push @ISA, qw(Foo Bar);
           }
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so no import! Then I expect no import.