  Using the recently derived higher spin gravitational Compton amplitude from
low-energy analytically continued ($a/Gm\gg1$) solutions of the Teukolsky
equation for the scattering of a gravitational wave off the Kerr black hole,
observables for non-radiating super-extremal Kerr binary systems at second
post-Minkowskian (PM) order and up to sixth order in spin are computed. The
relevant 2PM amplitude is obtained from the triangle-leading singularity in
conjunction with a generalization of the holomorphic classical limit for
massive particles with spin oriented in generic directions. Explicit results
for the 2PM eikonal phase written for both Covariant and Canonical spin
supplementary conditions -- CovSSC and CanSSC respectively -- as well as the
2PM linear impulses and individual spin kicks in the CanSSC are presented. The
observables reported in this letter are expressed in terms of generic contact
deformations of the gravitational Compton amplitude, which can then be
specialized to Teukolsky solutions. In the latter case, the resulting 2PM
observables break the newly proposed spin-shift symmetry of the 2PM amplitude
starting at the fifth order in spin. Aligned spin checks as well as the high
energy behavior of the computed observables are discussed.
