I’m getting confused about what question you’re actually asking.
The danger, as I tried to explain above, is when the RFM tries to transmit and there’s nowhere for the power to go. If it’s only receiving - and there’s nothing you want to receive anyway - then there’s no need to remove the antenna, and no need to have it either.
The emonTx automatically transmits; the emonPi only transmits when you enable it in emonhub.conf. The external antenna for the RFM is not the WiFi antenna, that’s internal, on the Raspbery Pi itself.