This school board is clearly not a patsy board elected primarily with the efforts of the teachers union. Their tough stand on the original letter shows this. They will likely accetpt this new letter though, since a judge would also likely rule that the original statement was ambiguous. I suspect the teachers will not follow this up with any teachers strike though. As a board I would consider any striking teacher at this point as a resignation.
I believe teacher strikes are legal in Pennsylvania ( used to be ) for a certain period of time .