Why would Marty arrange for the casino fire?

Question

At the start of S03, Wendy is keen to expand, while risk-averse Marty isn't.

In particular, Wendy wants to buy the Knarlsons' casino. In S03E02, Marty initially manages (behind Wendy's back) to convince Mr Knarlson to not sell.

Marty (while spying on Wendy's phone) then hears that Wendy and Helen plan to go back with a much better offer. Marty then goes to Frank Cosgrove and arranges to have the Knarlsons' rival casino go up in flames, the idea being that without that rival, the Knarlsons would be less likely to sell.

Marty is almost always the cool, calm, rational, risk-averse, non-violent accountant. Why would he carry out such a risky plan? The effects of this plan were hardly certain--e.g. it might have messed up, the men could've been caught (as indeed they were on camera and then later shown by the FBI to Marty), it might've been too late if Knarlsons had already signed the papers, it might not have changed the Knarlsons' minds.

Moreover, if the deal did go through and the rival casino went up in flames, then yes, this would have been good for business at the newly purchased casino. But on the other hand, Marty and Wendy would have been under great suspicion (they buy a casino just when that casino's rival goes up in flames), which is exactly the sort of risk Marty was seeking to avoid in the first place.

(This could of course just be bad writing but I was wondering if there's any plausible in-universe explanation for Marty's decision here.)

Answer 1

At this point, Marty does not want to purchase a second casino, and has been more than vocal about it. Wendy in fact has to go behind his back to talk to Navarro in the first place, and he then sabotages the purchase by talking to Mr. Knarlsons behind Wendy's back.

Marty knows that getting a new casino is tying themselves deeply to the Navarro cartel, when he actually wants out (and they had plans to leave, which Wendy unilaterally breaks). He knows there is no going back once the purchase is done. He also knows that they can't simply back off at that point.

By setting the rival casino on fire, his plan was to get the Knarlsons not to sign (as their casino would be able to secure credit to be renewed). This wasn't a bullet-proof plan, as you state: maybe the contract had already been signed, maybe the cartel would be able to offer enough money for them to sign either way... Regardless, it was the only thing he could try in such a short span of time without bringing suspicion to him.

The key point is that he wants to avoid buying the new casino at all costs, but cannot do so overtly without having the cartel take action against him. He had to stop this at all costs, do it fast and without it pointing back at him (which means without using the cartel resources). That's why it may seem out of character, because he is not normally force to act under these circumstances.