Nothing wrong with doing that in the slightest. Just because the user's home internet is IPv4 does not mean corporate side v6 services should be unreachable. Either way the user is going through a tunnel to reach things, it doesn't matter if what's inside the tunnel is the same as what's outside it... it's a tunnel! Doesn't even have to be IP!

Now that doesn't mean things can't get misconfigured or poorly set up in that regard but by no means is the concept just wrong, I have several clients it has been useful for.