The issue is the US government requirements for US carriers. The interview questions and level of security are different for the rest of us. I have never had an issue flying out of any French airport and it is much more pleasant than my weekly or more TSA experiences of the past.

OP was flying a US carrier, to the US, and was questioned as part of the 'security' required by the US government.

He wasn't removed from the flight for having nail clippers.