Hi,
That’s a good point and thanks for the provided solution. We will definitely include it in next plugin update, however I’m thinking of using $_product->get_children() instead of $_product->get_available_variations() with woocommerce_hide_invisible_variations filter – as far as I remember it will list invisible variations also (will have to re-test that though).
Will let you know here as soon as update is ready.
Best regards,
Tom