It needs to meet SQF requirements for storage as a contract service provider. They're providing storage as a service, and while they don't need to be a GFSI facility, you need to inspect and make a write up regarding how all SQF code concerns will be addressed. Allergens or hazardous chemicals stored on site? Justifiable so long as they're kept completely separate from your product. Pest control? If not, you'll need hard inspections for any material coming in from them to look for rodent damage or infestation. Building security? Test it, have that owner prove no one else is getting near your product and storage it with tamper evident wrapping. So on, so forth. Given that there was damage to your building, you can make this part of your crisis management and document the off site storage was necessary to promote business continuity. Go above and beyond, maybe even weekly inspections by you and your team to ensure all concerns you come up with are addressed.
At the end of the day, your food in that warehouse is at the same level of risk as an LTL carrier cross docking it at one of their hubs to transfer it between trailers. Auditors can be convinced you're doing it as safely as possible given the realities of your situation. Notify the CB, stress to them that it's temporary and you're taking active steps to ensure food safety during this crisis.
Your owners are going to push for that last option you suggested. I've consulted with two companies in the past who tried this (against our recommendation): one didn't get caught, the other had some explaining to do when an auditor asked to inspect inventory that was not on site.
Would you still consider them as a Contract Service Provider if there's no contract? My company is an older business and there's a lot of handshake deals made for things that gives me constant headaches. Don't get me started on approved supplier lists...
I don't think we're going to be able to get any information on anything else stored on site, but it is a segregated area, so outside of liquids seeping through walls, I'm not sure the risk would be high.
As previously stated in my reply I was typing while you replied, I'm unaware of the current pest control on site, but the laws of the area require it for warehouses so I would assume it's there until we get to inspect and not see it.
Everything is pallet wrapped that would be going over there, so tampering would be evident.
There is no war in Ba Sing Se! My previous job hid a bunch of stuff as well, and were quite adept at it. I recognize some of the things in my current company and I would suspect they could BS there way out of it since this is a temporary situation. This is part of what makes me want to get the certs to be an auditor, because I'm learning all the tricks.