The resaon given at the time was the ICAO "requirement" for RPT pax to be "contained" and that walking across the tarmac for jet operations is not really compliant.
It's not a requirement, it's only an ICAO recommendation as a risk mitigator ie to remove passengers from the dangerous ramp environs. If it was a requirement, there would be thousands of non-compliant airports around the world. Those that do it manage just fine.