The rules are pretty strict, designed to make it a level playing field. Basically the idea is that you shouldn't get anything - be it info, supplies or whatever - that isn't available to everyone else on the same basis. For example, one guy who lives in Berne, routed past his own house at about 1am. He stopped to chat to his wife but he couldn't stay there - he ended up sleeping in a park a few km away. He said that leaving his wife that evening was the hardest bit of the race!
This is what the rules actually say:
"If you are able to be in direct contact with a rider then it is fine to contact them to ensure that there
are OK and receive information from them. When communicating with any riders however we ask
that you to remember that this is an unsupported race and this means that support with remote
assistance including information is not permitted, especially assistance with navigation or the
finding of facilities and resources. The riders must do this for themselves. If watchers and
followers are found to be providing assistance to racers then they can contribute to their
disqualification from the race results. This includes discussion with riders through the Facebook
groups. Riders should also not be soliciting support through these discussions or any other
contact with followers. With responsibility on both sides and in the community of online following
we can ensure that all riders get an equal and fair chance to have this solo adventure."
http://reportage.transcontinental.cc/wp-content/uploads/2015/10/TCR-Race-Manual-2016-Iss1-May.pdf