I do not believe the BICS safety belt existed prior to NetWeaver 2004s (aka 7.0) - Prior to that release, the BEx Web presentation framework was ABAP-based, versus Java-based. Because ABAP runtime pre-dated BEx Web Java runtime and BI Consumer Services interface, I do not believe older BEx client runtimes such as the 'ABAP Web', or 'BEx Analyzer 3.x' (now obsoleted anyway) recognize the safety belt parameter. Perhaps in BW 7.4 this has changed, but my experience has been that older BEx clients as mentioned do not recognize thus do not honor the safety belt setting.
I just want to raise that, as some of the options in RSRT will still trigger the old clients such as ABAP Web.