I have also seen Conrail spray painted in big bright orange block letter DO NOT SALT THE RR CROSSING! on the side of a signal cabin once up in North Syracuse by the P&C Ware House off of Van Vleck Rd. I have not been up there in a while so I would assume that this message is still there.
I think anytime someone else wants to salt our lightly used crossings, it would be a blessing. Nothing worse than having to stop for every crossing to chip and dig out the flangeways on industrial spurs and sidings. The rule is, cut off you engines, and cut the crossings with them. However, more than a few times, we went on the ground because the ice would not yield. The elevators use potash or urea in their switches or crossings, even with crossing protection and few if any problems, and you don't have to stop.
The past few years, section was sent to all crossing prior to a trains departure to salt them down. It makes a big difference as you tend to get the work done and light power home. The last thing you want to do in the winter is take a taxi. Worse comes to worse, you send out the CATs.