The CEC officer sitting next to me at the moment makes the point that you don't "select" Seabees - you select the Civil Engineer Corps (a staff corps, not URL) and then at some point you are assigned to a Seabee unit. The Seabees are part of the CEC, but the CEC consists of more than the Seabees.
Are you asking if URL officers command Seabee battalions? If that's your question, then no. Some folks from outside the CEC might be assigned (usually supply, medical), but it's not something a URL officer would do.
Answer your question?