Important to note is the quotation from the pilots letter:
"Wie wir vernehmen mussten, führte dieser Zwischenfall bereits zu Beginn der Untersuchungen zur Entlassung zweier Mitarbeiter der Lufthansa Technik, welche die Arbeiten ausgeführt hatten"
Which I would like to translate as:
"As we had to learn, this incident lead to the release of two Lufthansa Technic personell who had executed the work, already at the beginning of the investigation."
So the from the letter it seem the first priority for the management was to sack the mechanics, even before the incident was fully investigated - which is probably the root of their fury.