All early Christians did keep the holy days of Christ and his food laws so the point is moot. Doing so was part of religion, culture and worship of God for thousands of years.
Is it? The history of early Christians and middle Christians and late Christians is full of those who do not keep holy days and food laws, nor circumcision. How about them? Jesus Christ never gave his holy spirit to gentile Christians without "benefit" of observing holy days and dietary laws?