Played Red Alert Aftermath map Island Wars Extreme on FFA skirmish once, the map with neutral AI hostile giant ants. One of the ants accidentally picked up an MCV crate and the Giant Ants team actually built up a base normally like other AI players (except the giant ants aren't hostile towards them, since they are the giant ant team). The weirdest part is a red coloured ant pick up the MCV crate so the MCV and the ant base is red, the same team color as mine(I was red too) so it's confusing for me.
In the end, the giant ant base wrecked a lot of the last standing computer player enemy units (this actually helped me a lot because many of my buildings were destroyed and funds/ore fields were depleted). The ant base and unit count was like 10 times bigger than mine but I still won that skirmish since we don't have to destroy neutral stuffs to win.