well, there is no option to disable the suicide function.
Only in case you are playing alone and not online, then there is a way to disable it.
The two platoonformers for the suicide platoons are located in
AI-Uveso/lua/AI/AIBuilders/Mobile Experimental-Air.lua
Your mod directory should be:
C:\Users\YOURNAME\Documents\My Games\Gas Powered Games\Supreme Commander Forged Alliance\Mods
To disable them you only need to set the priority of the platoons to "0"
You can find the two priority settings line in 436 and line 473:
Here are links to Git Hub to show you the exact lines:
https://github.com/Uveso/AI-Uveso/blob/master/lua/AI/AIBuilders/Mobile Experimental-Air.lua#L436
https://github.com/Uveso/AI-Uveso/blob/master/lua/AI/AIBuilders/Mobile Experimental-Air.lua#L473
To set the priority to 0 you only need to change the lines to:
Priority = 0,
If you do so have in mind the mod will instantly desync when played in multiplayer.