As mentioned a few posts back, the defense attorneys are supposed to provide the best defense they possibly can. Maybe this is GW4 attorney's method of doing so. Kind of like "go big or go home", I guess. Give it a shot, maybe something beneficial will come out of it. If not, at least he tried.
I did an online search of "subpoena co-defendant's attorney in murder case". Just a quick skim of the results IMO showed that this situation does happen when there are co-defendants and at least one takes a plea deal. IMO, when the co-defendant's attorney takes the stand, they will answer the general questions that are of the least importance. But, when they are asked specific questions about what they were told by their client, they state it's attorney-client privilege and don't answer. Of the few cases I looked at, the judge didn't force the attorney to answer. JMO
Thanks for looking into that tactic. It doesn't sound as though anything useful comes from this exercise, but perhaps its just going through the motions of objecting to the other party's plea deal. Just going on record.
It's also possible GW4's attorney would attempt some trick if he gets the attorney on the stand in a public court room hearing. He might play to the potential jury pool by publicly implying Jake's attorney is dishonest and that the plea agreement and Jake's testimony are false.
GW4's attorney may think he is doing his duty in fully representing his client. He may also want a "win" so badly that he's willing to do anything to see that his client is acquitted and released from jail, free to take revenge against anyone he feels harmed him.