Funny: that is exactly what I tried first when writing my last answer. I am not sure why this doesn't work but my guess is that it is due to how TikZ/pgf reads the argument to
\node. It obviously expands
\PrintSolutionsTFbut very likely after reading the options when it is too late. It doesn't see an option
0but sees an option
0were part of the option name). Such an option obviously isn't defined which explains the error. This is the reason why I put
\PrintSolutionsTFoutside of the path...
There is no standard way to tell TikZ/pgf to read those things as commands? Some use of brackets maybe?