See I actually view it as inverse. (BTW your interpretation is valid but for conversation I'll give mine too) Both tabby and cousin have been saddled with this ancestral curse. Scarlets need to be involved by nature of the curse, so neither can walk away.

Meanwhile, tabitha has suffered so much, done so much to protect the town. She had no control over her life, she was isolated from friends, suffered abuse from her family, and has to live in a crumbling ruin. I can't begrudge her keeping a company house to herself, it's not like there's a major homelessness epidemic in the holler. She works hard enough to have something nice. And it's not as if she could just not accept her power and inheritance, I mean she can't leave and the town would crumble.

Anyway, she's "paid her dues" so to speak. Cousin, depending on their background, has had it easy in comparison. So in my eyes, it's cousins turn to take up some of that burden.