Actually, Aelle typically takes 26.8mm posts once go to the next size below theoretical [28.6 -(2 x 0.8) = 27.0]. However, it was not uncommon for manufacturers to ream Aelle frames for a 27.2mm post so that they only had to stock one seat post size.

The question is whether the tube has been reamed for 27.2mm or not. You say a 27.2mm post inserts a "couple of inches". Normally an oversize post will not insert below the bottom of the binder slot, which is typically not 2 inches long. If it is going past the bottom of the slot, it sounds like it was reamed, but not very deeply. The other clue is to look at the sides of the binder slot for parallelism. Putting a 27.2mm post in a frame meant for a 26.8mm post will open the slot by about 1.2mm at the top. Conversely, putting a 26.8mm post in a frame meant for a 27.2mm post will cause it to be noticeably pinched, by about 1.2mm, at the top of the slot.