Depending how your data tables are set up and related, the option of adding both Person and Comment to the rows will probably be easiest.
Often when you do it like this (again this depends on what your tables are and how they are related) you will need to add some type of measure to the values field to get your pivot to filter properly when you use the slicers. The measure can be something simple like just a count of the comments. It will probably show up as 1 for every row in your pivot but that doesn't matter. You need the measure to "unify" everything going on in your table relationships, pivots, and slicers. If you don't want the measure column to show in your final report just hide the column in excel.