Are the owner benefits from Impersonate Tax Collector part of an action?
Looking at the FAQ for Lords of Waterdeep, there is a question which seems to answer this question:

Q: If a plot quest gives me resources for having taken an action, did I gain those resources as a part of taking the action?
A: No. You gained the extra resources from the effect of the plot quest, not from the action itself.
Note 2: The benefits of plot quests, and the rewards for completing a quest, never count as being a part of an action.

Since your plot card(s) are what are giving you the benefit of the Owner's action, this would seem to indicate that you do not receive the extra resource.