WARNING: The following contains spoilers for Fear Street Part 3: 1666, now streaming on Netflix.
In Fear Street Part 3: 1666, we discover the Goode clan has driven a conspiracy for centuries, getting Shadyside to believe that Sarah Fier was the witch behind the curse and subsequent massacres. Solomon started it at the Union settlement when the town was a Puritan village, and now, Sheriff Nick has continued the charade so he can summon killers to get blood sacrifices for Sunnyvale's prosperity. However, after seeing how Solomon started the spell and covered it up, it's clear that his plan was always destined to fail.
His incompetence is first seen when Sarah visits him after escaping the mob at Union. Rumors are flying that she's a lesbian, which is heresy and a gateway to Satan, per the bigots' thoughts who live there on the estate. The fact that Pastor Cyrus Miller murdered kids, and now, his daughter, Hannah, is the lover Sarah's been spotted with, Sarah has a red flag on her back that makes her guilty before trial.
But when she gets to Solomon's home, as he's a family friend, he hides her out of sympathy. However, Solomon should have let her be taken because she's providing the perfect cover for his occult ways. It makes no sense to shelter her because deep down, her family is expendable.
After all, her brother, Josh, was killed by a possessed Cyrus, so if the town wants to lynch Hannah and Sarah, Solomon will get off free and be able to summon killers whenever he needs to enrich the lands. But as he harbors her, she slips under his home, finds the witch's lair and summoning circle, and realizes that he's the villain.
This leads to her escaping topside, only for Solomon to arrest her after cutting off her hand. But seeing as he came up from the back, he could have just stabbed and killed her. That would have made sense because she could have told her friends, her dad or the mob at the hanging where Solomon's supernatural lair was.
He risks it all, and admittedly while it's plot convenience, it doesn't paint him as smart. By doing this, when Sarah's hanged, he allows her to curse him, and in the finale, when Nick gets his hand stuck in the gooey hellish gateway in the lair, it's Sarah's spirit that haunts him as he sees the victims.
This allows Deena to kill Nick and end the curse, but it can all be blamed on the man who almost ruined the alibi. Had Solomon just let the mob grab Sarah, she wouldn't have figured out what he did, thus, her spirit wouldn't have endured to break Nick's mind. Ultimately, Solomon's stupidity does allow Sarah to become a curse; one that marked the Goodes and waited for the right chance to screw them over.
Netflix's Fear Street trilogy -- Part 1: 1994, Part 2: 1978 and Part 3: 1666 -- based on the works of renowned author R.L. Stine, is available on Netflix. The series stars Sadie Sink, Kiana Madeira, Ashley Zukerman and Gillian Jacobs.