Contractor’s scaffolding accidentally sent water careening into basement of new construction house three months ago. 
Water on floor was removed a few days later, but white stuff is still on inside of zip and on studs. HVAC is not yet in service, and there is no construction heating.
Foundation was poured in May 2022.

Do you think this is mold? It is easy to brush off, has a dust-like quality
Contractor says it is concrete splash from foundation pour. 

If you think it is mold, it is now being entombed by spray foam … is that a problem, or will it ‘go away’ when hvac in service, which will not be until after drywall installation?

Thanks