I've looked everywhere that I could to find the prefab for the Heavy Scientists on the new Oil Rig. 
I used PrefabSniffer and tried using each of the Scientist NPC's but weren't the right ones or didn't spawn.

Using entity.spawn heavyscientist works perfectly, but I'm changing the asset from K1llYou's ZombieHorde to make it a little different. 

If anyone knows the location of it in the assets let me know!

Thanks!

assets/rust.ai/agents/npcplayer/humannpc/heavyscientist/heavyscientist.prefab.
maybe.

https://github.com/JVCVkrSzVqsfEcwJqk7N/Rust-Docs/commit/e2fb1902ab7bea13ceacc377c5bb902f703372b0

prefab

assets/rust.ai/agents/npcplayer/humannpc/heavyscientist/heavyscientist.prefab
​

item (suit) 

scientistsuit_heavy or -1772746857

assets/rust.ai/agents/npcplayer/humannpc/heavyscientist/heavyscientist.prefab | Won't work for some odd reason. I don't know if it's because the event needs to be called first or what happens. Normal scientists like junkpile, gunner, etc work but this one doesn't.

because the new heavyscientist has walk on a new entity of the oil rig they probably crudely made it work for now will probably be fixed in the future so you can use it for land.

I realise that it might be "off topic" but have you tried "kitting" out a scientist "bot" with heavy armour and boosting health and aggro ? , it might be a temporary fix but it can be placed anywhere on the map ?

I could, but I'd like to add their exact loot table, which I don't know lol.