Lock PI-Star to a single YSF reflector

[W9RIX]

Hello,
I have a ZumSpot running PI-star 4.1.6 in duplex mode to act as a gateway for a local repeater. There is a particular person in the area that keeps changing the reflector to a different room. He does this without asking and does change it back when he's done. I suspect he does this to be a nuisance but I haven't been able to contact him to ask. What I would like to do is set the reflector permanently and configure the software to ignore any "on air" changes. I have created a net YSFHosts.txt file and removed all entries except the reflector I want and set (in the experts setting) the new hosts file. I have also made sure that WiresX passthrough is not enabled. Even after making these changes, I see his call sign in the Dashboard and the YSF Network shows "Not Linked". Any ideah what I might have missed or have any suggestions on how to best resolve this situation?

Thanks,

Rick - W9RIX