As far as obeying law in Ethiopia and International framework, Every country, including People's Republic of China, should be allowed to invest Ethiopia. Though some people say its investment can be the new form of colonization, workers of the Chinese factories are paid to an extent, and it boosts Ethiopian economy to the extent that the country records rapid growth of GDP. It means real economy is also flourishing.
But, judging from the fact that Ethiopia is now economically attractive because of low wage and minimum safety, economic growth will stop after average wage of the country is equal to that of China.
So, Ethiopia will have to seek ways to nourish highly-skilled workers who are worthwhile getting high salary.