I am confused by the statement that $\Omega^\text{framed}_1(S^3) \cong \mathbb{Z}$ which I came across as an application of the Pontryagin-Thom construction for showing that $\pi_3(S^2) \cong \mathbb{Z}$. I understand that there is a $\mathbb{Z}$'s worth of framings on a given knot that are not pairwise framed cobordant to each other but why does the type of knot not seem to matter? My guess is that all knots in $S^3$ are cobordant, is this the case and if so why?
Thanks!