The Correct Use of 'Both'

Both “My uncle will arrive tomorrow.” or “My uncle will be arriving tomorrow.” are correct.

The above is part of an answer given in a newspaper column promoting the correct use of English.

Correct usage has required the sentence to be Both “My uncle will arrive tomorrow.” and “My uncle will be arriving tomorrow.” are correct.

I have written to the editor receiving no reply and have to treat that silence means consent.