Yes that's why he has reaction, because he can turn into omega and kloff activate it with medicine then SA him... You can see later in story his struggle and addiction of medicine because he was always in pain
SPOILER
.
.
.
IN SECOND TIMELINE aeroc want his 6 children so badly that he was willing to use that medicine again to turn into omega, but this time kloff mate with him without using medicine, (and point that kloff and aeroc are imprinted so kloff technically smell Aeroc omega smell) and due to this reason Aeroc turned into omega without side effects
IN THIRD TIMELINE author explain this concept , in some medical examine Aeroc was having symptoms but he didn't have memories his past life so he went to Dr, result of the test was show aeroc can turn into omega and can get pregnant, test result is alpha = blue and omega = red but Aeroc result was purple
Is Aeroc an omega in the second timeline. Kloff said he was giving out a sweet scent when they where together talking when he pushed him against the wall outside