Cannibal & Clown
Barbecue & Chili: "A deep bond with the Entity unlocks potential in one's aura reading ability."
Pop Goes The Weasel: "A deep bond with the Entity unlocks great strength."
A deep bond?
Can it be that these guys are THE most motivated Killers of the bunch to work for the Entity?
Or does the Entity think they're doing the best job out of all Killers?
Or...something else?

Comments
Both benefit from the Entity, for LF he has a second chance after he failed his family and the Clown can go act out all of his urges and desires without consequences.
Both werent physically tortured by the entity, both were granted enhanced abilities by it.
Leatherface gets paid twice compared to any other Killer and the Entity likes the Clown so much he helps him personally with his Bamboozle ability.
The problem with that is The Shape: Doesn't have mercy for anyone but 1 little boy in 1 movie. (As far as i know.)
Even if he's enslaved by the Entity, i don't think that would present itself as a problem to him, as he'd get to kill more and more.
In fact, i'd go so far as to say he might prefer it this way: Every 5-10 minutes, he gets 4 people to kill.
Exactly, so there'd practically be no problem making him a Killer.
But he does feel, they've shown that.
Well if LF is the most motivated or is doing the best job out of the killers
Then the entity needs to raise its standards
Bond
noun
1.
a thing used to tie something or to fasten things together.
"she brushed back a curl that had strayed from its bonds"
2.
an agreement with legal force, in particular.
synonyms: promise, pledge, vow, oath, word (of honor), guarantee, assurance; More
verb
1.
join or be joined securely to something else, typically by means of an adhesive substance, heat, or pressure.
"press the material to bond the layers together"
synonyms: join, fasten, fix, affix, attach, secure, bind, stick, fuse
"the extensions are bonded to your hair"
2.
join or be joined by a chemical bond.
Plenty of room for interpretation here
It's because the Entity is a chubby chaser.