That would be a pretty big reach don't you think =p . People like [Alexander] Pierce and Garret were recruited because they became disillusioned. Ward was recruited because he was a lost teenager. That motivation and lack of choice didn't exist for Triplett or his grandfather. If his grandfather was a Howling Commando and decided to not retire and help create SHIELD then that means he did it with the likes of Dum Dum Dugan and Howard Stark, making him [potentially] one of the founders of SHIELD. And since Zola acted independent of SHIELD in the beginning, there does not exist a motivation or a reason for Tripletts granddaddy to ever betray his country to the enemy he spent years fighting against. And no the potential for his granddaddy being a sleeper agent does not exist. I highly doubt an African American would of ever been recruited by the Nazis.
"If that's what it means to be wise, I guess that means I'll be fool all my life" - Naruto, after Jiraiya has told him to wise up and give up on his friend.