If I get it correctly, your point is that one requires copyright for open source software to be viable, by opening up a revenue stream to support the (free) open source part. This is true.
You can make money form open source on either:
1) Selling alternate, source closed licenses. (MySQL for example) 2) Selling support, consulting. (Red Hat, many others)
(1) requires copyright. (2) maybe less so, but without the open source licenses, which require copyright law to work, the software wouldn't exist to begin with either. Red Hat uses trademarks (which really are similar to copyright) to reinforce their position. So does Mozilla.