The only theory offered for the formation of the high temperature olivine is that it formed close to the Sun or another star.
HOWEVER, the theory of radiogenic heating in comets early in the Solar Systems history could also explain this.
This theory is controversial ONLY because it would raise the possibility of life on comets. Note though that radiogenic heating is a leading theory for the origin of the heating in the icy, comet-like world of Enceladus (they both have water jets.)
Note as well the theory the olivine formed close to the Sun or a star would not explain why Kuiper belt object Quaoar apparently still has internal heating, whereas radiogenic heating WOULD explain it:

Chilly Quaoar had a warmer past
Mark Peplow
Crystalline ice suggests remote object has radioactive interior.
Published online: 8 December 2004.
http://www.nature.com/news/2004/041206/pf/041206-7_pf.html

Bob Clark