Thats a false statement, developer mode does not allow you to install with same credentials that ovi store provides. (Only if you have R&D certificate, which normal users don't have). In open mode you can use AEGIS_FIXED_ORIGIN to install with any origin. Developer mode only adds develsh shell that has same capabilities that ovi origin has, and you have to run develsh with aegis-exec if you want to run with those credentials.