Because this is a relativity question, we must consider two perspectives:
Perspective 1: that of an observer watching the milk speed by. Answer -- no, because the milk is (hypothetically) traveling as C, like a photon it doesn't experience time, so it cannot spoil, and the independent observer so reports.
Perspective 2: that of the milk, hypothetically traveling at C. Because the milk is traveling at C, the speed of time, there is no time dimension in any meaningful sense. Lacking a time dimension, the milk isn't in a conventional four-dimensional spacetime frame, therefore it cannot spoil, indeed nothing at all can be said to "happen" in the conventional spacetime sense.
There's a reason why the speed of light is special, and why relativistic frame comparisons break down at that speed -- primarily, there aren't four dimensions essential to forming a basis for relativistic perspectives. So, if we somehow get around the mass-moving-at-C limitation, time still poses an insurmountable problem.
Perspective 1: that of an observer watching the milk speed by. Answer -- no, because the milk is (hypothetically) traveling as C, like a photon it doesn't experience time, so it cannot spoil, and the independent observer so reports.
Perspective 2: that of the milk, hypothetically traveling at C. Because the milk is traveling at C, the speed of time, there is no time dimension in any meaningful sense. Lacking a time dimension, the milk isn't in a conventional four-dimensional spacetime frame, therefore it cannot spoil, indeed nothing at all can be said to "happen" in the conventional spacetime sense.
There's a reason why the speed of light is special, and why relativistic frame comparisons break down at that speed -- primarily, there aren't four dimensions essential to forming a basis for relativistic perspectives. So, if we somehow get around the mass-moving-at-C limitation, time still poses an insurmountable problem.
Further reading: http://arachnoid.com/relativity