It could also be the reverse, if they think Shannon is the guilty one. Maybe they are putting pressure on Josie to tell the truth, and taking the opportunity to speak to her about the situation with Gus while Shannon is not there?
My thinking is this is much less likely, for a couple of (related) reasons. But it centers around: JM is the one they arrested, not SM.
Let's say for the sake of speculating here that they did use this arrest as a strategic maneuver to separate the two of them for questioning. That they basically found and used a slap-on-the-wrist kind of violation they had noticed on an earlier search as an excuse to do so. (And side note, depending on the exact nature of the violation, it's possible that it was even something they could have chosen to arrest SM over instead, or both of them at the same time.)
What we know happened was they arrested JM, who then had to drive (alone) to the police station ~2 hours away, be processed, whatever else had to be handled there as part of the arrest, post bail, and drive back home (again, alone). SM was at Oak Park Station when the arrest happened (and possibly might not have even been able to leave it since JM had to take a vehicle, and SAPOL might still have the ones they seized, and we don't know how many they had to begin with).
If they engineered this situation, they did it in a way where, of the separated time that SAPOL bought for themselves, they filled JM's time with busywork while keeping SM free and clear for the entire time, and at the possible crime scene location. Something like 3 1/2 to 4 hours of travel time alone, wasted, plus all of the time at the police station having to actually focus on the charges the arrest was based on (and being restricted by whatever laws are in place there for how police have to handle people they have in custody and are charging with a crime).
And the other related reason: JM would be uncooperative and angry at the police station after being forced to drive ~2 hours to deal with a petty charge after/in the middle of everything that's happened between the family and SAPOL up to this point. ~2 hours of seething in the car about it, knowing that it was something trivial, and knowing it was going to be another long drive back. Almost certainly would have demanded a lawyer, because again, arrested and being charged with a crime, then sat in silence until the lawyer arrived, then dealt with them through the lawyer. If it's something low level enough to be allowed to drive yourself there, the charge isn't going to be serious enough to scare (and so pressure) you into spilling any secrets you've been holding, just enough to irritate/enrage you. It would further burn any bridge that might be remaining between JM and SAPOL.
I think the one they chose to arrest was the one they didn't have any hopes of having a good working relationship with in the future on this case. That they could count on it shutting a door, or saw it as a door that was already shut. This will be an antagonistic relationship going forward between them, any trust that may have once been built up, demolished. And I think the one they wanted to talk to alone was the one this arrest bought the most time to talk to alone, at home, in a setting where they can just talk, or where they can be walked through or shown anything that might be relevant on the property instead of having to squander that precious time on all of the bureaucratic routine kerfluffle that accompanies an arrest. Where they can still maintain a
pleasant and
helpful tone as they talk instead of accusatory. That's SM. Whom they could still have been conceivably getting a significant amount of information out of, alone, while JM was no longer in SAPOL custody and was making the long drive back home again, alone, and quite possibly fuming at SAPOL the whole way.
My own speculation and opinions only.
www.abc.net.au
