This is my opinion. The engineer of record is ultimately responsible for the final design, and every body that contributes to the final design must be under the EOR's responsible charge. It doesn't matter if the person contributing to the design is a fellow engineer licensed in the same state, an engineer from another office, a right out of school staff engineer, summer intern, licensed 1099 contractor or consultant, unlicensed 1099 contractor or consultant, or the uber driver you bounced engineering concepts off of, they are all under the EOR's responsible charge. Being a W-2 employee is not a requirement to be under the EOR's responsible charge.
If you hired a consultant to provide any kind of service (performing calculations, drawings, or just providing advice), it is still up to the EOR to completely verify the design prior to taking responsibility of it by apply their seal.
Unless your contract with the consultant included final seal by an engineer in the state of the project, then I do not see a licensing issue. If this was an employee, you would just fire them if you felt they were under performing. The fact the consultant is (I assume) a contractor to your company does not change this relationship. You simply "fire" them (no longer do business with them) and move on. I don't consider this a licensing issue. This would be different if they were submitting work to the owner of course, but you are essentially just subcontracting out labor and your company is still fully responsible to the owner.