I have difficulty in understanding the underlined part. Could anyone do me a favor? Thanks a lots.
I had been to Hanoi, and returned obsessed with the notion that I had no professional justification left if I did not at least try to make the point that North Vietnam, despite all Washington argument to the contrary, was inhabited by human beings... and that to destroy their country and their lives with high explosives and petroleum jelly was no way to cure them of their defects... This conclusion, when expressed in printed or television journalism, was generally held to be, if not downright mischievous, then certainly non-objective, within the terms of reference of a newspaper man, on the grounds that it was proclaimed as a point of view... To this of course there could be no answer whatsoever, except that objectivity in some circumstances is both meaningless and impossible.
The phrase "This conclusion" refers to his notion that North Vietnam was inhabited by human beings. Since that is perfectly obvious it is also perfectly obvious that that is not really what he means in the first place. He challenges the reader to figure out what he means.
The term print journalism refers to reporters who work for newspapers and magazines, while broadcast journalism refers to reporters who work in television or radio. The term television journalism (as used here) refers specifically to reporters who work in television.
He answers charges that he lacks objectivity with the statement that in some circumstances objectivity is impossible.