1. but - except; apart from; other than
There's no other word for it but rude.
2. be all for - strongly in favor of
I'm all for it.
3. rationalize - attempt to explain or justify ( one's own or another's behavior or attitude)with logical, plausible reasons, even if these are not true or appropriate
Many people rationalize that kind of impolite behavior by claiming they're multitasking.