How could the Lord be "marginalizing" Sly? Explain.
"Marginalizing" seems an odd choice of words for interaction between individuals, since it implies a systemic problem that develops over time to shut one individual (or a group) out of "meaningful participation in society" (Definition from Wikipedia, link below).
The Lord does indeed intend to make Sly the butt of his joke by convincing the drunkard that he is, in fact, a Lord, rather than the drunk tinker that he knows himself to be, but this act in and of itself cannot produce Sly's marginalization from society.
The Lord may, in the course of his everyday life, repeatedly engage in behaviour that contributes to the marginalization of individuals in Sly's circumstance, but, as far as we know from the play, this is his first interaction with Sly. Marginalization is a result of actions through time, and not the result of one moment of interaction between two individuals. This moment might be better termed The Lord bullying Sly or treating him as a plaything, but I think that "marginalizing" is too global a term for this circumstance.