I suppose she could put the earbuds under her muffs.

The only issue I see as a problem is that which has already been mentioned- a lack of aural awareness of the surroundings as she works.

I would like to point out that we may be confusing terms and types.
In my mind, 'earbuds' refers to the style that nestles in the outer ear with no clip support.
The style that often is sold as 'noise suppressing' actually goes into the ear canal very much like earplugs do.
http://www.headphone.com/guide/by-headphone-type/

I think the 'earbud' style would be safer than the 'ear canal' style in this case.