This is a hardcoded hack.
There are (meanwhile..) 6 variables that are "exported" from the way-context:
costfactor, turncost, uphillcostfactor, downhillcostfactor, initialcost, nodeaccessgranted
"nodeaccessgranted" is then turned explictly into a lookup-variable and propagated from the way to the teminating node.
This is needed to enable routing over bicycle-routes with access=no/private nodes.
However, there's not (yet) a general concept to propagate data from the way to the node context.