I googled a bit, its con_filter_text_out "" instead of the other, tested it, should work for you, but u cant force clients to use these vars
Code:
con_filter_enable "2" // def. "0", Filters console output based on the setting of con_filter_text. 1 filters completely, 2 displays filtered text brighter than other text.
con_filter_text "My Nickname" // def. "", Text with which to filter console spew. Set con_filter_enable 1 or 2 to activate. Setting on the playername or part of it makes all entries with his kills/death light up
con_filter_text_out "" // def. "", Text with which to filter OUT of console spew. Set con_filter_enable 1 or 2 to activate.