Do you have a proof that some galaxies do not in fact, contain neutron stars, thus supporting your claim?
And besides, the tiering system uses the Milky Way as a standard for galaxies, which contains many neutron stars, which ALL needs to be destroyed in order for the whole galaxy to be destroyed
Usually, when a galaxy is destroyed, the implications is that it is entirely destroyed (and in cases they actually show said explosion, we see nothing left afterwards), rather than "oh it got destroyed but maybe a star remained despite the space being empty and there's no implication something survived". Assuming that stars survived this when we got no proof for them still existing doesn't seem right to me.
Besides, the same logic for galaxy you mentioned can also be used for universes too. Nothing changes except the scale of the blast