Ironclad: Feature or oversight??
Turns out Vasari Starbases are immune to mines. At least Advent mines. I just witnessed an Orkulus merrily strolling its way out of a massive Advent minefield. Not a single detonation. I mean, is the base not big enough to be detected?
Mines could have been a valid strategy to counter the Orkulus being built in your grav well. Trap it to the edge of the grav well until it can upgrade enough to survive the mines or the attacking player can bring in scouts to clear the mines.
Mines don't get used much, they should be useful like that.