Timers have nothing to do with it, nor do older versions of mIRC. The point is that your code is unnecesarily complex.
Code:
if (%rkickmsg == 1) { goto rand } 
ban $1 %bs | kick $chan $1 %kbmsg $+ ) %kick.txt
:rand


can be written as:
Code:
if (%rkickmsg != 1) ban $1 %bs | kick $chan $1 %kbmsg $+ ) %kick.txt


Yes, your code still works, but it's harder to read and doesn't follow clear logic.