So, you think some EC bought a small Eaton C/H panel just to gut and us as a transfer cabinet?
My guess - the panelboard was already there and contained the desired circuits to be connected to standby power. Maybe there never was a generator before but it was planned to someday put those circuits on one.
Owner purchases generator and transfer equipment - with built in branch circuit overcurrent devices - easy install is to remove guts from original panel and place that assembly in there since it fits easily.
Just a possibility - it could just be a way to make that transfer equipment into flush mount type and the cabinet was not there to begin with. That panelboard is probably cheaper than trying to buy any other cabinet to put it in and just discard the interior.