You are definitely not off base, but your associate is not even in the ballpark. In the first place, your safety is always a top priority. If you are uncomfortable walking through a dark parking lot and valet parking is available, then you should use it. It is important to be extra cautious on a business trip since you may be operating in unfamiliar territory.
As for your employee chastising you for using the valet, a couple of questions jump right out. In the first place, he is your peer, and that means that he really is not in much of a position to chastise you for anything. Secondly, there must be more important matters to discuss with one's associates than valet parking.
If he continues to fixate on this topic, you should tell him that you are going to use valet parking whenever you think it is safer, period. Then let him know that it is time to move on and discuss matters of real importance to your company and customers.
One day he may understand that people who fixate on the parking lot typically miss the main event.
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