Actually, and unfortunately, that IS the IT policy.
Definition of tamper:
1
: to carry on underhand or improper negotiations (as by bribery)
2
a : to interfere so as to weaken or change for the worse used with
with <did not want to
tamper with tradition>
b : to try foolish or dangerous experiments used with
with
c : to render something harmful or dangerous by altering its structure or composition <was charged with
tampering with consumer products>
You literally got caught tampering with surveillance equipment and were immediately terminated.
I'm sorry.
What you did, in their perspective, was 100% wrong, and what they did, based on the handbook, is 100% legal and correct.