use (someone or something) as an excuse (for something)

To create an excuse (for something) based on someone or something or what someone or something has done. I was getting really bored, so I used Tom's cold as an excuse for us to leave the party early. This is your last chance to show us you belong in this company, and you can't use the quality of your computer as an excuse this time.

use someone or something as an excuse

to blame someone or something (for a failure). (See also use someone or something as something.) John used his old car as an excuse for not going to the meeting. My husband was sick in bed, and I used him as an excuse.