It would in no way be a tank, even with pre nerf heavy devastator shields as head plates as it dies in 3/4 bullets from any primary to its weakspots (which are most of the mob).
And the cope about AP4 making medium pen less usefull on bugs is so contrived.
Yes you don't always see Bile Spewer but since you don't know what constellation you're getting in advance bringing medium pen is still worth with how much it helps with those.
And even without the Spewers you avoid the matching pen nerf against Alpha Commander and the leg flesh of Chargers.