Resolution:
Please execute RFC as tRFC which will execute in the background.

To make an RFC a tRFC, please follow the below changes-
1. Configure the RFC one-way in the TIBCO side using SAP R/3 adapter (this does not affect anything in SAP)
2. Make the RFC call in SAP ABAP/4 with "DESTINATION &ltdestination> IN BACKGROUND TASK"

So, in effect TIBCO side has no control over an RFC's behavior as tRFC. Also, note that step 2 is mandatory from SAP side to make a call tRFC.

For more details on how to execute a one-way BAPI/RFC as a tRFC using R/3 adapter, please refer to TIBCO Adapter for R/3 User’s Guide: Chapter 9 Advanced Features -- > Invoking BAPIs/RFCs Using Transactional Semantics in SAP R/3