Still not getting it - it's not the Commander making a brave decision to sacrifice his ship, it's the Commander going along with the hothead Decius because there really is no decision involved. He isn't about to make a "safe return", but is instead stalled already.
That his final actions would have any effect on war, one way or another, is unlikely.
1) The Commander already attacked, several times - one more offense will not make any difference in the "acts of war" department.
2) If this was a test of the ship's capabilities, it was a success (since survival is not the Romulan way, and Decius already did decide it was a success after the initial attacks and told the Praetor as much) and the war can now commence, or a failure (because the ship was exposed and tracked, and her being late tells the Romulans back home as much) and the Commander could just as well wait for a tugship inside the RNZ.
3) If this was the first shot in a campaign, a special forces strike to pierce the RNZ defenses, it connected nicely enough, and there's now a gap for the Praetor's armada to exploit - the Commander is already retiring from the battlefield as planned, and his actions no longer matter.
4) If one invisible attacker almost got away, Kirk is not justified in thinking that destroying that one would make the UFP safe from immediate further attacks of the sort, by dozens of like vessels. So the Commander isn't disarming the Star Empire with his actions, not in the eyes of the UFP, even if his ship really is unique.
The Commander really comes off as spineless, doing Decius' bidding just because. Is it brave that he removes himself from plaguing this universe further? Hitler got no points for his all too late departure. Earlier on, his generals, expecting execution back home, got no points for theirs. If anything, Kirk now can report that the Romulans are as ruthless and inhuman as they always were reputed to be.
(No disagreement with the other points. This is a well done episode even if the plot itself doesn't make much of an impact.)
Timo Saloniemi