i think ur boss means he want to distribute all the cool air evenly in the big area...
imagine 2HP at one side only, definitely difficult to cool down evenly...
otherwise install cassette type air con right middle of your area with 2HP...

anyway, i think multi split only benefit to the users tended to switch on 24hours for whole house cooling... perhaps the compressor just around 3HP compressor serving 4 air con concurrently... same concept like big building with a huge water cooling tower on the roof top... if standalone air con, 4 unit with 1HP may cost more...