It wouldn't make any sense for this to be a contract dispute
issue as they cut the cable while the contract negotiations are
still in progress. Unless it was meant as a warning. . . .

Typically, if it's actually a 'Union' thing, they'll wait until
AFTER a strike is called before doing anything of this nature.
The idea is the cable now has to be repaired by folks who are
untrained / unskilled in the process, thus the time needed to
repair it would take MUCH longer.

Now I wouldn't rule out a disgruntled ex-employee but as to
ideas of who and why, I couldn't possibly think of anything
that would make any sense.

*shrug*