I'm not sure MS will testify before the jury voluntarily or at TD's behest.
I can think of three possibilities, of many, for the jury and TD to consider:
1) MS is innocent of planning to kill TB and the evidence, or lack thereof, will speak for him
2) MS appears guilty of planning the truck theft and killing TB but the evidence is not substantial enough to prove his involvement
3) MS is guilty and the evidence, in its totality, seems to indicate his willingness to plan and execute TB's murder (my personal position)
In all three scenarios, this late in the trial, I find it more likely TD will try securing a lesser charge for his client through other means than a confession of MS's part in the crime on the stand. I don't think TD will want to to risk the Crown grilling MS on all the finer points of his testimony and potentially revealing his culpability instead. MOO.
If my hunch is wrong, and MS does testify, I'll probably have a difficult time believing his claims. The moment MM suspected his involvement in TB's murder, MS, like DM, shifted blame on the co-accused and denied having anything to do with the actual murder. I don't think MS will change his interpretation of events on the stand. I sense the Crown made the right move in accusing both DM and MS of the same charges. Only the perps know what happened on May 6, but both consented to steal the truck, subdue the owner, burn the victim, and "celebrate" the next morning on a job well done. The Crown may push for the FC or premeditation angle as they tie up loose ends, but IMO, they've made the case for either or both well. It'd be especially poignant if the Crown wraps up its case this week, though - sending a prayer for strength for the Bosma family and friends. MOO.