I've been listening to WGR all week and it sounds too me like consensus is that Allen will probably play very little, if at all. I don't think whatever happens in Pittsburgh will really play into it. Regardless of if they win, I don't expect them to win 2 games in a row (and if they do, does anyone think the Bills are worried about going there?)
Bottom line is you have to weigh likelihood of not getting that second home game (pretty unlikely) and how much it could impact our chances (even more unlikely) vs likelihood of Allen or someone significant getting hurt (it happens to teams every week) and how it would impact our chances of winning (if Allen goes down we're likely screwed.)