Curious to know, he seems to be the arrogant type and he seems to have a bad relation with the Habs somehow.
Walsh is Halak's agent, and pumped his tires big time during Halak's time here. Which was fine, but he also did it at the expense of Price (e.g. tweeting his stats compared to Price's, questioning why Price was getting a start over Halak, etc), which I think pissed off a lot of people in Montreal. It was the eye of the storm re: the Halak/Price debate and people were irked that he was stirring the pot in the city just to benefit his client.
Basically he leans on social media to stir up fanbases and try to put pressure on teams to cave to his clients. He pulled a similar stunt when Sarnia drafted Pavel Zacha in the import draft and Walsh took to twitter to rip Sarnia's GM personally, more or less calling him an idiot for drafting a player to a team that Zacha publicly said he wouldn't sign with. Lo and behold Zacha eventually did sign with Sarnia and a lot of people (myself included) saw Walsh's outburst as a calculated move to try to humiliate Sarnia into caving to whatever demands Zacha and Walsh had already put on the table.
That being said - I don't think there's anything personal between Walsh and the organization. His twitter stunts are probably annoying but at the same time, business is business. He has tons of NHL clients so obviously he's good at what he does. As someone posted out, he wouldn't do his radio segment if he didn't like Montreal, but I imagine he took a lot of heat from Montreal fans on twitter during the Halak/Price days.
(He's also a really good follow on Twitter and is vehemently pro-player which makes for some interesting reads and insights)
He's Jiri Sekac's agent, but to my knowledge (just based on who he tweets about) he doesn't represent anyone currently on the Canadiens.