Using this logic, how might it play out for Red Hat Enterprise Linux? They are now requiring payment in exchange for access to the source code.
CLAs may become standard for all serious open source projects for similar reasons.
There's a reason why CLAs, including signed permission from your employer, have been standard for GNU Project contributions since forever ago, even if it weren't tied to this particular issue. It gives the FSF free and clear rights to the code to enforce copyleft without the potential for legal snags regarding ownership and permission to distribute later on down the line.
Maybe that's just the GPL due to how it's formulated.