Dolohov's promise appears to be reiterated in the comments as "if it is within my power, I will not allow you to come to harm."

Strangeweale, well, he did interfere in an MLE investigation, leading to Chloe not being in a state for V to torture and off her himself and the complete misplacement of the Selwyn kids. He might well take exception to someone usurping his perogative there.