Yeah, I know that they’re beatdown hardcore/doom rock, but could they be added as a side project of Infant Annihilator’s members, now that IA is on here?

No, Black Tongue is not a side project.

It’s not?

Okay, turns out in the band's inception it was billed as a side project. That's my bad there.

Nonetheless, the side project rule is being winded down to the point that only mods will be able to add them on the typical case. Also, while Infant Annihilator does have that internet/meme notability, I'm loath to consider a non-metal band that started as a side-project of a band that initially had one non-very non-metal album.

EDIT: as an addendum, I forgot that the side project must be made by notable musicians at the time. At the time IA were definitely a meme, but I'm doubtful on how much people knew the musicians beyond the random people watching their music video for the memes.

Their last album was considered by many their most metal-influenced yet, just like IA's. It definitely took me by surprise after being used to their (sometimes entertaining) "chugcore".

This chat doesn't really go into if "Nadir" was considered. It's still chuggy but a good amount of extreme metal influence for possible inlcusion.

https://www.youtube.com/watch?v=oqYASEv1KYM

That album was already brought up:
viewtopic.php?p=2817526#p2817526

And the consensus among mods back then was it's still beatdown hardcore:
viewtopic.php?p=2825622#p2825622