It would be disadvantageous for a team to take him via the rule 5 draft, and even of they did, he is not a massive loss. But much like last year when he was also exposed to waivers, most teams seem to be avoiding him anyway. It is possible his reputation from St. Louis is still an issue.
The Sox now have TWO pen spots on the 40 man roster. Maybe they make a Rule 5 pick, but hopefuly they are looking to add some actual MLB talent. But if it was a Rule 5 pick, hopefully they grab a pitcher they can at least bury in the back of the bullpen. A couple of intriguing names per various websites around the internet include Colorado LHP Riley Pint and San Diego RHP Jordan Guerrero. Both of whom do have triple digit heat, but as you can guess, obvious issues with control/command. But that is to be expected for any hard throwing lottery ticket left exposed...