I simply tested it on a machine that has yet to have .net 4 installed.
The machine itself is simply a server that has nothing else but sql server installed.
I have sett the launch condition "minimum .net version" to .net framework 4.0.
I have run the installation environment that doesn't have 4.0 framework and it allowed full installation without alerting.
Attached is the installation file.
This is an urgent issue.