The American Rose Society classifies larger roses with smaller blooms as miniatures. The buying public often won't. The ARS establised the classification criteria. You can't fault the breeder for utilizing the established criteria to classify his/her rose.

From my experience, the buying public will accept a taller plant with smaller blooms as a miniature because it's most often the smaller flower they are buying when they order a "mini". Very often, when a breeder gives the classification, the ARS changes it. If you bought a multiflora or wichuraiana climber with small flowers as a miniature, you'd condemn the breeder/introducer for misleading you. Even shrubs with small flowers are criticized for not being what they've been classified as.

These arbritrary classes are most useful for those who aren't sufficiently familiar with roses to make their own choices based upon their judgement. Once you are familiar, you can often browse the parentage and description to make your own choice, most often with acceptable results.

Get used to it, the flower size determines the miniature classification. Larger roses with smaller blooms won't make it in the market because "the blooms are too small". Larger minis with flowers in the expected size range have been successful for years. Look at Minnie Pearl for just one example. She's not a "climber", yet she is often seven feet tall locally, and she still sells.