In "Aunt Jennifer's Tigers," the limitations that bind Aunt Jennifer in life don't bind her in art. So, at least she's got that going for her. Aunt J's needlework allows her to experience a world of deep green forests and prancing brave tigers (oh my!) that is incredibly different from the real life that she leads—the one that is weighed down by the sadness and strictures of her marriage and her gender. Art in this poem is a kind of freedom, a freedom accessible to everyone, even the disempowered.
Like a prisoner locked up for life, Aunt Jennifer never gets to be truly free in this poem. Even when she creates her art, she is weighed down by Uncle's wedding band. That's some hard time she's doing.
Even when Aunt Jennifer dies, her tigers continue to prance on the tapestry. (No batteries required!) Thus, art provides the ultimate freedom from death.