I would have to guess that someone who does not understand how, when and why positive songs about the land of Israel were sung by generally "leftist" folkies is either relatively young (born after 1970) and/or has no knowledge of the hugely leftish orientation of most of the Jews who went to the land in the mid 20th century and the leftist folkies in America who supported them in their anti-Capitalist enterprise. The founders of the kibbutzim were predominantly secular "back-to-the-land" quasi-communists from the various laborers/workers/unionist movements of the era, of which Pete Seeger was a prominent part. Are you unaware that conditions and attitudes in countries change over time? Business, conservative religious and upper class power-seeking politicians radically changed the character of Israel over the past 60 years and you'll find few folksingers singing Zionist songs these days.