You can do it with Hold (but need to explicitly release it): Graphics[ReleaseHold@
Thread[{Hold[RandomColor[]], {Disk[{83, 69}, 2], Disk[{34, 32}, 2],
Disk[{68, 90}, 2], Disk[{75, 84}, 2], Disk[{69, 91}, 1]}}]]
Not sure that Unevaluated is supposed to be used like that.