This likely has nothing to do with Node, but my guess is that whatever program "xtermPath" points to is executing the string passed to -e by passing it to bash, which, as a non-interactive invocation probably isn't loading .bashrc in the same way (I see you have -i to your own invocation...), and it is evaluating $PATH there, and then it is passing the already evaluated string to "/bin/bash -x -c -i", which is the one you're seeing exporting the path, but it has already been evaluated at that point. Try, instead of "echo $PATH", executing a one-line shell script that does the same, and see if the behavior changes. Alternatively, if you expect your path modification to work generally instead of just in an interactive shell, put it in a more appropriate place (although I did think that .bashrc was the right place for this, but it depends on OS and various other configuration options...).
Hope this helps!
Jimb Esser