How have courts in the United States dealt with the issue of threats of imprisonment if a co-accused refuses to waive extradition?

The applicant referred us to United States of America v. Cobb, [2001] 1 S.C.R. 587, 2001 SCC 19, and United States of America v. Shulman, [2001] 1 S.C.R. 616, 2001 SCC 21. In Cobb and Shulman, which were heard and released concurrently along with two other cases arising from the same facts, a judge in the United States dealing with another co-accused had stated that if the accused persons still in Canada did not, in effect, waive extradition they would face maximum sentences in the United States. As well, the American prosecutor threatened that if the accused persons resisted extradition they would be put in prisons where they would “be the boyfriend[s] of a very bad man”. These comments were found to be an abuse of process and the charges were stayed against the applicants.