I still find it very odd that the feet would melt from the bottom up when the heat source is above them. I would expect the mounting part to melt first and the feet simply fall off rather than the bottom of the feet melting ... that should be the coolest part of the computer.
I have seen rubber materials react badly with my daughters hand cream, suntan oils, lotions, etc. which gave the appearance of melting, but it was more like disintegrating. I have also seen the character markings on keyboards totally disappear from a chemical reaction with her hand cream.
I have also had rubber feet on electronic gear like routers and speakers melt into gooey blobs when they were in extended contact with oak desks and furniture which had some kind of lacquer finishing on it that created a chemical reaction.