in the above poem I don't criticize immigrants of any particular background only, again, the act of mass/economic/capitalist immigration itself, so what you said, again, is false and defamatory

Change the record. Get this into your head, if you can: you don't have to criticize immigrants of any particular background in order for your views to be racist.

The Oxford English Dictionary defines 'racism' as follows:

The belief that all members of each race possess characteristics, abilities, or qualities specific to that race, especially so as to distinguish it as inferior or superior to another race or races. Hence: prejudice and antagonism towards people of other races, especially those felt to be a threat to one's cultural or racial integrity or economic well-being; the expression of such prejudice in words or actions. Also occasionally in extended use, with reference to people of other nationalities.

Unless you can show that that poem doesn't exhibit "prejudice and antagonism towards people of other races, especially those felt to be a threat to one's cultural or racial integrity or economic well-being", Ruth's correct and you're the one who owes her an apology.