This idea originated in Louisiana where they established a 9-3 vote to execute. Given the universally accepted truth that black men were disproportionately executed, there is an understandably strong sentiment in the African American Community that opposes the death penalty. Louisiana figured that if they could keep 12 person jurors limited to 3 African Americans, they could continue the executions of black men.
The way death penalty-qualified juries are selected a prospective juror is excluded from the jury if they oppose the death penalty. So, the prosecution starts with a stacked deck in favor of executions. But, to be safe and assure that if one or two African Americans end up on the death-qualified jury, the one or two votes opposing the death penalty that would come from them will not be enough to save the accused from executions. 10-2 is not a compromise between the Florida House proposed 9-3 vote and the Florida Senate (that voted to require unanimous verdicts of execution), it is a continuation of the disparate application of the death penalty to African American men.
It is doomed when this latest Florida legislative effort reaches the United States Supreme Court.