Luke drove while also contemplating the capture plan.
If Luke's guess was correct, then the two robbers might be hiding in the Maserati, looking for an opportunity to escape.
Capturing ordinary robbers in a stakeout wouldn't be difficult, but these two were different as they might have bombs on them.
Even Muriel Balldini might have been strapped with a remote-controlled bomb, which would allow them to maintain better control over her.
The Maserati wasn't driving fast, which made Luke believe that the robbers were probably also observing and waiting for a chance to make a run for it.
To be on the safe side, Luke also called for backup; he didn't redirect the second squad, instead ensuring they continued to watch Muriel Balldini's home.
Since there were two robbers, Luke wasn't sure if they would split up and act separately. If one was in the car and the other at the house, moving the second squad might allow the one hiding at the house to escape.
