The Democrats of that time had a large conservative bloc consisting of southern and western Democrats.
Goldwater voted against those bills.
So-o-o-o....why didn't Goldwater run as a DemocRAT?
“So-o-o-o....why didn’t Goldwater run as a DemocRAT?”
Because he was a Republican.
A western Republican who had more in common with the conservative southern Democrats of the 1960s than he did with the liberal eastern establishment Republicans who dominated the GOP and who worked actively to defeat him.