You're wrong. According to the article, the ACLU "...said that punch-card voting machines would ''disproportionately disadvantage'' African-Americans, Latinos, and Asians...". Voter-punched machines are less accurate and less reliable than machine-punched machines. Lower income districts probably opt for cheaper machines. A case can be made for being "disproportionately disadvantaged" without saying that it implies minorities are less capable. Stick with what the ACLU actually says, vs. what the author of the article implies it means.
Perhaps a "case can be made." It is you who chose not to "stick with what the ACLU actually says," but to add that "voter-punched machines are less accurate," and to assume that low income districts are minority districts and that low income districts probably would buy cheaper machines.
As you wrote, "stick with what the ACLU actually says." By doing so you may be able to grasp what they meant rather than having to defend what you hope they meant.