[Look, if messing around with an empty desk keeps Lalo mostly sane and happy, Saul is perfectly fine letting him do just that. It's gonna be a pain in the ass later, he's sure, but for now, sure! Have at it! Mess around with the desk, there's not much there that's worth keeping secret yet.

He winces as Lalo tells his story, rubbing the back of his hand on reflex, because ow. And while he's sure there's more to this story than Lalo wants to share, because Lalo probably doesn't think any of the other details are relevant, a counter-strategy for this case is pretty cut and dry.]

If he was supplying underage girls with alcohol, that's a solid enough defense right there. Concerned for the safety of the girls, you took action into your own hands. The guy wouldn't take "no" for an answer, and stabbing--drastic though it may have been--was the fastest way to ensure the girl could continue on her way.

[As with any story he's telling, this explanation of Lalo's totally really altruistic actions are punctuated with pointing and talking with his hands. At the end, he gives Lalo a double point, a serious expression on his face.]

I mean, think about it. If you hadn't stabbed him, who knows what could happen? If anything, you minimized her possible trauma.