A specialist referral process at Kelsey Seybold

Hi

I met my PCP (Kelsey Seybold family Dr) to get a referral for an orthopedic (Dr. Gregory, Memorial Herman). PCP said Kelsey Seybold will deny my request because Dr. Gregory was not Kelsey Seybold's in-network specialist even though Dr. Gregory is my insurance's in-network specialist. Was my PCP right? I've never heard of this.