That is the expected behavior of most (if not all) boost converter. As it should be obvious from the schematic, when there's no switching happening, the supply current just flow through the inductor and high-side switch/diode to the load.
If you need to disable the output completely just add one pass transistor as switch, or use some non-direct topology (4-switch buck-boost/SEPIC/Cuk, I dunno if that warrant the additional complexity if you don't need buck-boost in the first place)
Some boost controller can be used in SEPIC configuration, some are not. My cursory google-fu showed there's some Russian guy making SEPIC 3608.