Let me try one more thing: "since he made an investment with this company"

Schedule C has no Balance Sheet. He made an investment. That is him, a person, which is the same as the Sched C person, because only Corporations are their own entity. This is his K-1. His business EIN is for his business operation. His SSN is him, and his own investments. His Schedule C is part of Form 1040. Notice the difference between Schedules and Forms.