I have ATmega8 and I write its codes in assembly only using AS6.2 SP1.
I agree that, in case a register is redefined, the warning is useful in general; it was discussed here years ago.
But, as you know, there are always exceptions to the rule ;)
For example, in some projects, redefining a register with different names when it is used as a temporary one in different functions (called exclusively) lets the source code be clearer (without extra comments); mainly if there are many of such register.
So I thought that perhaps an option to disable this warning (in a project) was included in recent versions. By searching so far, I couldn’t find this option but perhaps I missed it.