Per the DOT page you cited, aerosols used for personal medicinal purposes or are toilet items ARE permitted in checked baggage. Although the OP will have to confirm that his gf had items along the lines of hairspray/deodorant and not WD40 or spray paint, your blanket statement that "Aerosols have been prohibited from checked bags for many, many years" is inaccurate (or at least incomplete).

Depending on what was confiscated, the OP may have a legitimate gripe.