That’s what he did. He sent the FO to have a look.
But as he said afterward, no pilot likes the feeling of sitting in the cockpit staring at a potential raging fire in the belly hold while having no comms, twiddling his thumbs and waiting for somebody to come tell him WTF is happening!
Here’s a better solution.
Before boarding, make it SOP to positively check and confirm comms with the ramp via a working headset.
His company actually FORBID this because it ”wastes time” and might delay boarding!
Safety be damned. OTP is the first priority. All other priorities rescinded.