You actually wrote 'could always do' not 'could do' which has a completely different emphasis. In English it implies encouragement as in 'should do' without the risk of sounding rude as in 'you should do this or that'. As you had read my paper with 'great interest' I think my use of the word 'should' was a fair reflection of the sense of your email message. You may if you wish publish the whole of our private communications on this message board.