In that case I would disagree with your analysis of the issue, the launcher is not the problem.
The main culprit is the game installer when using Steam, it does not add the correct registry values so each time you see the DX message.
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\GamersFirst]
[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\GamersFirst\APB]
"directX ShipDate"="04.18.2011"
[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\GamersFirst\APB\1]
"Installation Language"="1033"
"Installation Path"="E:\\STEAM\\STEAMAPPS\\COMMON\\APB RELOADED"
"Installation Type"="110101119"
"SocialPopupWasShown"="True"
[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\GamersFirst\APB\APB Reloaded]
"Initial Version Installed"="1.19.5.783457"
"Installation Language"="1033"
"Installation Path"="C:\\Program Files (x86)\\GamersFirst\\APB Reloaded"
"Application Group Folder"="GamersFirst\\APB Reloaded"
"Tag"="live"
"Installation Type"="110101119"
"SocialPopupWasShown"="True"
Without the above it will always show DX trying to install, please note these are for my drives C and E.
You may not want a workaround but consider the information above as more detail to your BUG report.