I really think it was because of the audience pressure. The governor of the state is here, celebrities, VIPs, and you cannot stall the fight for too long.
I would have liked a 5 minutes recovery time, the same way they get for kicking nuts and eyes pokes. I know there is technically "nothing illegal" in those calf kicks, but I can tell you that they are THAT IMPORTANT, and game changers, for not bending rules around them.
It will happen again, trust me. Don't you remember O'Malley's fight against Andre Soukhamthath ?
It happened right in the middle of a round, and if the ref decided to stand up the fighters instead of having Andre keeping the fight to the ground if I remember correctly (that was quite suspect at the time by the way), well Sean would have clearly not been able to stand on his foot. He ended up winning the fight by unanimous decision, very weird.
Jimmy will be fine, I can tell you he will bounce back and be better than ever. He learnt as well something in this fight, don't march forward like a bull offering your leading leg to be chopped.