You could also modify the ASSMod part for ULib if you wanted.
if ASS_VERSION then
ASS_BanPlayer( att, att:UniqueID( ), ( 7.5 * 60 ), "Automated temporary ban" )
into
if ULib then
ULib.kickban( att, 7.5 * 60, "Automated temporary ban" )
Here's your hook.
hook.Add( "PlayerDeath", "killedTooMuch", killedTooMuch)
And line one of your code will need to look like this:
function killedTooMuch( ply, _, att )