A321 pilot reported after documenting discrepancies into the aircraft logbook; the aircraft was taken out service due to corrosion and cracks on the rudder.

Narrative

Garbage Write-ups" per ZZZ TechAfter preflight inspection on Aircraft X for FlightABCD ZZZ/ZZZ1; multiple discrepancies were discovered and notated in the aircraft logbook. The first ZZZ maintenance tech walked into the forward galley and angrily yelled into the flight deck at myself and the FO; "These are garbage; write-up's. I'm going to NEF (Non-Essential Flight) them and you will be out of here in 20 minutes." I replied; "Even the broken metal strip on the rudder?" He then entered the flight deck and reiterated his displeasure for me entering discrepancies into the logbook as he inspected the broken crash axe strap (also a discrepancy). I then asked him if we should board if we will be clear of maintenance in 20 minutes. (Which I did not think was feasible given the seriousness of some of the discrepancies.) He then replied "this is my airplane now; and I'll call when I think they should board."After this visibly upset tech left the flight deck a flight attendant came up to the flight deck and told us that the same tech told them that "the pilots don't want to go anywhere."After technician inspection; the rudder apex strip was found to have "heavy corrosion" (per logbook entry of corrective actions). The aircraft was pulled out of service for the rest of the day (much longer than 20 minutes) and I'm sure that any A&P would not categorize this as a "garbage write up". Furthermore; the fact that a pilot found metal so corroded on the rudder; that the rivets/ fasteners were popping off; the metal was broken ; rusted; and peeling back from the airframe; on a walk-around is astonishing. This corrosion took an extended period of time to form. I'm sure there were multiple inspections and checks that should have caught this much sooner than I did on a simple pilot preflight inspection. Furthermore; after reviewing the photos I took of this corrosion and referencing the "corrective action" it appears the corrosion is much worse than this small section. There appears to be cracks along the rudder apex strip both above and below the main area of damage (which was the only portion that was temporarily repaired; according to the corrective actions in the Logbook). If left unchecked; rudder metal corrosion could lead to catastrophic failure of critical aircraft flight control surface resulting in mass loss of life. I'd highly recommend a joint Company/ FAA investigation into this incident; aircraft; and fleet type. I'd recommend a re-inspection of Aircraft X with a FAA maintenance inspector; a full audit of the "temporary repair;" a random audit corrosion inspection of other A321's with the same approximate age; and issue an AD if deemed necessary. I'd also recommend a full investigation into the behavior of the tech reprimanding the flight crew for entering discrepancies and labeling them as "garbage wrIte-ups" in addition to a full CRM course encouraging maintenance to behave in a professional safety-forward manor when interacting with flight crews."