genesis.tex: qualify Praos design claim

ouroboros-consensus/docs/report/chapters/future/genesis.tex

@@ -60,7 +60,7 @@ \subsection{Speculative mode}
 
 The Praos chain selection rule (choose the longest chain) was explicitly
 designed for a context in which all nodes in the network are present from the
-very beginning and are always online. The Praos security analysis
+very beginning or somehow had one of the current chains when it joined and are always online. The Praos security analysis
 \cite{cryptoeprint:2017:573} essentially shows that when the honest nodes in the
 system are all following this protocol, they will end up with a common prefix,
 with disagreement possible only about the most recent $k$ blocks. This means that