Yes, you have some sort of deniability, but it's probably not plausible (did you report the supposed theft to the police? why not?).
But your biggest problem is: they actually do find you easily and while they don't have definite proof, they will definitely suspect your involvedment and start an investigation. Why become a target at all if it can be avoided?
Yeah. Dash still has a lot to go through to achieve complete anonymity. Even if it uses Coinjoin mixing via masternodes, third parties can still track you if they manage to trace the masternodes. Therefore, for complete privacy it would be best to combine both masternodes and Zero Knowledge Proofs technology to eliminate any traces that would link to your real identity. When both are used, it doesn't only obfuscate the sender/receiver of the coins, but also the balances and other sensitive information.
Many say that the team behind Dash has most of the masternodes under their control, making it less decentralized than I've thought. Since it requires a collateral of a hefty sum of Dash, not everyone could afford this and run their own masternodes. The only way possible would be via masternode shares, but the masternode would still be owned by a third party. Using only TOR will not give you complete anonymity. You would need to combine other privacy solutions to be able to achieve the desired level of anonymity. Therefore, combining TOR + VPN, and masternodes + ZK-SNARKS will preserve your privacy.
Nevertheless, I hope that Dash could improve over time and become a solid cryptocurrency to bring privacy to the mainstream world. It has managed to gain a lot of improvements over its codebase, with greater consensus than Bitcoin itself. Only time will tell if Dash could remain one of the leaders in the anonymous cryptocurrencies market or not. Just my thoughts