I get unsolicited offers via godaddy frequently. If someone searches for a domain and its already registered, Godaddy always offers to broker a sale whether your a customer of theirs or not. So that's not unusual at all.
But yeah the commission thing, that's messed up, seems like a shift at Godaddy maybe to start pushing the fee on the seller rather than the buyer? But it is complete BS if the seller isn't affiliated with GoDaddy. The broker should be working on behalf of the buyer, and thus, charging the buyer. Its always a sticky situation in this industry, who is the broker REALLY representing here, and do they try to play both sides of the fence. Of course they do try and work both parties so that they can make a sale and hence a commission.
I do appreciate that Jonathan (son of famous domainer and DancerA's former local buddy from Penticton) did at least disclose the fee, and he did ask you for a NET or GROSS price, so I feel that Jonathan was doing the right thing there. He disclosed it, no foul there.
HOWEVER, it is also possible that GoDaddy is trying to double dip, charging a commission to BOTH parties. He mentioned a 25% commission to the seller. He did NOT mention of that commission was the ONLY commission. GoDaddy could be telling both parties there's a 25% commission in order to now take a 50% cut. I wonder if that's possible.