In that case, yes, it’s most likely a memory limit. Watch your virtual memory and see if the process for safari hits a certain size consistently. Start other applications to consume memory and see if the 1169 drops to a lower number.
Just a guess, but these things usually go in terms of powers of 2.
So, if you had unlimited memory, my guess is Safari would crap out when you have something like 2,048, or 4,096, or 8,192, or 16,384, ..., .... number of windows open.
It will stop, one way or another. Not sure how OS X behaves but once in Windows I got my enter key stuck and launched some 500 odd instances of IE before I got it unstuck. The entire computer came to a grinding halt and I could not even shutdown. Had to power it off.