It was a little unusual in that she had her CFI/CFII and other ratings, taught & flew charter before getting picked up for an ANG C-130 pilot slot. She was an exceptionally competent pilot and great teacher. But the situation is definitely the exception rather than the norm.
That's actually fairly common amongst the Guard. They're usually hired based on having a job/career that meshes well with the part time ANG life-style. In the AF, it's not uncommon for Pilots/WSOs to have a CFI and do part time instructing - not so much for a side revenue, but because they enjoy doing it.
Being a CFI is one thing, but taking corporate trips is a little tougher... because of currency, recurrent training, etc. Most companies aren't going to pay for that if your schedule has no flex... maybe during breaks in training, but that won't hold up forever.