Why did William Davenport have to label his opera, "The Siege of Rhodes", as recitative music?

"The Siege of Rhodes" (1656) is recognised as the first English opera. It was the first in the English language and was subsequently revived in 1659 and 1661.

The initial portrayal was in private homes, but later public presentations had to appease the Lord Protector, one Oliver Cromwell. Puritans did not like opera, hence the name change.

https://en.wikipedia.org/wiki/The_Siege_of_Rhodes