My thinking: If he was just a fellow starship commander, why would he be so gung-ho for these trials? He would be eliminating his own occupation.
Good point! He is not just a fellow starship captain but a commodore and older than Kirk, so his days of commanding a starship may be over soon. So he looks forward to a promotion to admiral and contributing to "a revolution in space technology as great as warp drive" may be his ticket.
Apparently, him and James Kirk know each other well enough to almost call each other friends, yet this doesn't prevent Wesley from being outright mean to Kirk when he called him "Captain Dunsel", especially since Kirk hadn't volunteered for these tests. It's almost like "The M-5 is going to end your career but I don't mind."
For all we know Wesley is looking forward to orchestrate a fleet of M-5 controlled starships and his familiarity with the system puts him on the top of the promotion list.
It's interesting that he never considers that M-5 may have lost its marbles. I'd say that as a starship commander he should have taken that possibility into account but failure to do (and report) so may have been an issue in a hearing. And what about this "I'm going to take a chance he's not just laying a trap"? Was he hoping he could save the Enterprise
or was he mostly interested to see Dr. Daystrom and the M-5 survive intact?
I can imagine that Wesley had to listen to the same stuff as Kirk did in "Court-Martial":
"I'm thinking of the service. I won't have it smeared. Either you accept a permanent ground assignment, or the whole disciplinary weight of Starfleet command is going to light right on your neck."
Looks to me that Wesley chose exile on Mantilles...