I am not sure what point you are making here.. that he is good or bad at PK?
From what i've seen, he is fine. Nothing to write home about, but also no Bergeron. I mean.. Montreal is 29th in terms of PK, so how good can you say anyone is? I looked at plus minus, and he has -10 but you dont get those numbers unless you are in those PK situations (lol ie: Armia is +1), and Savard has the same numbers. Montreal is 5th worse in the league with 4.27 penalties per game, so it's possible that MSL has no choice but to use him.
I think in the perfect world, Suzuki would be 1 or 2 C, with Dach being the other to split offensive workloads, which would split the other team's best assets between them. In theory that would help both players produce offensively. With Newhook and Dach out, MSL seems to want to use Monahan to the same effect.
However, Dvorak is injured, Evans can handle some of the PK work and guys like Mitchell are meh. Monahan gives MSL that other option, especially as his faceoff percentage is high. I dont know that Monahan would be used in PK optimally (id rather see him on a top 6, especially with another Center with a different strong side on faceoffs), but the point is that he can, and i dont think he looked out of place doing it.