Well, we’ve given Medals of Honor to soldiers who killed themselves by diving their plane into enemy positions or by throwing themselves on a grenade to save their comrades.
Yes, to my mind blowing oneself up voluntarily for a cause is most certainly not cowardly.
Now killing CAN be cowardly, as when you kill yourself because you can’t face those you’ve wronged or the consequences of your own actions. But it isn’t always cowardly, and especially so when doing so in the service of a cause, even when I disagree with that cause.
So were the kamikaze pilots of WWII cowards, to your mind? Misguided, to be sure, and fighting for a bad cause, but to my mind they were quite obviously superbly courageous.
The issue is of course complicated by the fact there are difference kinds of cowardice, such as moral cowardice vs. physical cowardice.