|Self righteous and occupying the "moral high" ground, or|
at least positioning oneself to appear to be good one
Alternatively, Jacob only used this practice after some goats were born with the spots without intervention. He was concerned that these goats would have offspring without spots that would rightfully belong to him, but Laban would claim them because they have no spots. He used the sticks only for his legitimately earned spotted goats.
One can argue about the plausibility of these justifications, but that is less important than the implication that it would have been wrong for Jacob to rob Laban, even though Laban was a thief. There are other interpretations that might not support this approach. Perhaps the most compelling point is Jacob’s assertion that he served Laban loyally with all his strength, working and be consumed by scorching heat during the day and frost by night.