Probably because the only air bridge collapsed while an Aer Lingus flight was boarding a few years ago...
Collapsing due too faulty maintenance the aircraft was not damaged in that incident. The floor collapsed but the airbridge continued forward causing the aircraft to shudder. Aer Lingus I believe received a settlement from the DAA due to the disruption of flights caused (aircraft was made non-op for 5hrs). The DAA are responsible for the maintanance of the sole airbridge, with the CAA responsible for the running of it.