What strikes me that the s1 set up is in several ways the reverse of the s2 set up, as very visible in this episode: here, Ivanova is the newbie in the core command staff, Garibaldi is the one who is close to the commander and knows him from the old days. Whereas Ivanova is the one who knows Sheridan, Sheridan himself is the newbie, and Garibaldi even at the best of times was never that close to Sheridan. (This, btw, is why Garibaldi's s4 storyline doesn't have quite the intended impact for me - I mean, it's horrible for Garibaldi in any case, but JMS clearly went for a "best friend forced to betray best friend" scenario, and Sheridan and Garibaldi simply weren't. With Sinclair, the same scenes would have been even more powerful.)

Also, Sinclair at this point clearly doesn't like and distrusts G'Kar (no kidding, since G'Kar had tried to hand him over to the Vorlons and in this story is involved in an attack and some piracy), and sympathizes with Londo. While Sheridan's very first encounter with Londo painted Londo as untrustworthy and powerhungry (he never got to meet first season Londo), whereas to him G'Kar always comes across as well-meaning, if at times frustrating. (He's not aquainted with "hooray for sneak attacks, as long as they're ours" G'Kar, either.)

Garibaldi stopping Londo from going after G'Kar with a gun finds its echo in Sheridan stopping G'Kar from going after Londo, and so forth.

Garibaldi's fondness for cartoons is by and large an endearing character trait, but I can understand why Jerry Doyle felt it was shameless product placing by the WB...