Congress passed numerous fugitive slave laws, provided a number of ways of enforcing those laws, and in every case were an individual state tried to restrict the enforcement of the laws the courts ruled against them. If that was a grevance then it was a made-up one.
The only relevant question is did those violations render secession legal? Texas v. White says no.
Not entirely accurate. Texas v. White does say secession is legal if done with the consent of the states, as you pointed out in the quote you provded.
According to Kentucky v. Dennison, none. "...there was "no power delegated to the General Government...to use coercive means to compel" a state governor to act.
I'm not really sure why you picked this particular case since it has nothing to do with secession. If you're looking for Article IV support then perhaps a more appropriate case would be Prigg v. Pennsylvania where the court ruled that individual states could not enact laws that interfered with the enforcement of the fugitive slave laws. However, the court also ruled that the fugitive slave laws were federal laws and that states could not be made to enforce them.
Because the federal government would never allow a city or state to provide sanctuary to a protected class...right?
"I'm not really sure why you picked this particular case since it has nothing to do with secession."
I didn't. Kentucky v. Dennison is listed in constitutional law texts under chapters dealing with secession. See post #157. I find it quite telling that Texas v. White is barely mentioned.