Someone needs to remind Holt that immigrants were detained and sent back home at Ellis Island, too.
ELLIS ISLAND HISTORY - ARRIVAL
Despite the island's reputation as an "Island of Tears", the vast majority of immigrants were treated courteously and respectfully, and were free to begin their new lives in America after only a few short hours on Ellis Island. Only two percent of the arriving immigrants were excluded from entry. The two main reasons why an immigrant would be excluded were if a doctor diagnosed that the immigrant had a contagious disease that would endanger the public health or if a legal inspector thought the immigrant was likely to become a public charge or an illegal contract laborer.
-PJ
Shipping companies tried not to transport any people with contagious diseases, both for the health of their passengers and because they had to provide return passage when not admitted.
BM