Google Assistant expose optional

I’am using google assistant for a while to control my lights, it works great! But then my nephews arrive… and start yelling to google to turn on/off/on/off lights etc…

What i did in the past was stopping my Nginx Proxy Manager so google could not reach my home assistant.

What i would like to make an entity exposure optional by a boolean for example by:

#  Woonkamer
light.woonkamer_lampen:
  name: Lampen
  room: Woonkamer
  expose: "{{ states.input_boolean.bedienbaar_vanaf_google.state == 'on' }}"

But this is not working (of course). What can i do to make it work, or are there other ways to dissable google accessing my lights for a short while.

Many thanks in advance!