After Charlie explains to Don why he should look at the entire first shooting chain Don says you'd be safe shooting "Tim" to start a chain that leads to the killing of "Bob" because you have no motive for killing "Tim". However you DO have a motive for killing "Tim", it's just that your motive is less visible.
Correction: This is not a "motive" in the sense that the FBI would interpret the term in. So the statement is still valid in that it's not a motive that a criminologist would normally consider as such.
Correction: This is not a "motive" in the sense that the FBI would interpret the term in. So the statement is still valid in that it's not a motive that a criminologist would normally consider as such.