Back office costs and relevance to operational performance

I'm currently doing some analysis on a company whose financials are split into several distinct business units and HQ admin (back office) costs. I currently have a simple PL for each individual business unit as well as a statement for the back office costs.

I had a discussion with my boss today on how meaningful the PL for the individual business units are if we aren't able to allocate the back office costs appropriately to each business unit. (Note that this is in the context of a potential carve-out transaction)

My boss argued that looking at the PL for each individual business unit independently from the back office costs is completely useless. While I understand that a buyer would of course need to assess the back office costs to be allocated to any particular business unit, I felt that looking at the PL for each individual business unit separately would also give additional perspective on the trading performance of a business without costs that don't necessarily pertain to the actual operational aspects of a business.

Just curious to get thoughts on whether you think there is merit to look at a business unit's PL both independently and with allocated back office costs as I wasn't really able to have a clear argument at the time and it has sort of been in my head for the remainder of they day.....