There was not another buccaneer in all the Caribbean who would have denied himself the pleasure of stringing Colonel Bishop from the yardarm, and by thus finally stifling the vindictive planter's hatred have increased his own security.

But Blood was not of these.
Moreover, in the case of Colonel Bishop there was a particular reason for restraint.

Because he was Arabella Bishop's uncle, his life must remain sacred to Captain Blood.
And so the Captain smiled into the sallow, bloated face and the little eyes that fixed him with a malevolence not to be dissembled.
"A safe voyage home to you, Colonel, darling," said he in valediction, and from his easy, smiling manner you would never have dreamt of the pain he carried in his breast.

"It's the second time ye've served me for a hostage.

Ye'll be well advised to avoid a third.