pex in commercial space

Hi guys , still working on a way to make the Inspectors gig work, in the mean time, studying what i can, and trying to look at any properties i deal with at work through the eyes of an inspector. Yesterday while in a 1400sf office condo we own and have leased out, i noticed an interesting plumbing modification the tenant has done. This space has 4 offices, 2 with small hand sinks, we had them installed for a old Dr tenant 10 years ago, professionally installed, all permits pulled. All drain and supply lines are copper, i seem to remember the plumber back when we did it, said it had to be all copper in the this commercial building. What i found yesterday was a new sink, in the far back closet of the this space, they make a small kitchen. Knowing there is NO way to get normal drain over there, i had to look and see what they did, and found they put a 5 gallon bucket in the cab underneath for the sink to drain into, in the bucket was sump pump, which is pumping 50' up and across the ceiling and tapped into the the copper drain. I know that setup is 110% wrong. To feed this sink they tapped into the existing copper and ran PEX through the drop ceiling down to the new kitchen sink to feed it. I'm pretty sure the execution and install are not to code, What about the PEX, is it not allowed in a commercial space like the plumber told me years ago? Thanks

source https://www.inspectorsjournal.com/topic/18807-pex-in-commercial-space/?do=findComment&comment=172142