Another reason Giants should be rooting for the Eagles to beat the Cowboys:
As difficult as the Giants schedule is for the last 9 games of the season, the Cowboys schedule is ridiculously easy. Giants had all their softer opponents in the first half and the Cowboys have most of their weaker opponents in the second half. Specifically, Cowboys schedule after the Eagles game is: Seattle and Buffalo at home, followed by the Redskins on the road, Miami at home and back on the road in Arizona. They could win all 5 of those games and almost surely will win 4. The Cowboys have already played the hardest teams on their schedule: Patriots, Jets, 49ers and Lions. Their last 4 games of the season has the Giants twice sandwiched around games against the Buccaneers and Eagles.
My point with all of this is that, excluding the 4 division games the Cowboys have left against the Eagles and Giants, they should win a minimum of 5 out of 6 of the other games. That would put them in prime position to win the division.
By contrast, the Eagles have at least some difficult games remaining on their schedule: Bears, Jets and Patriots. So even though they also have the same weak opponents left from the NFC West: Seattle and Arizona, unless I am grossly underrating them, I don't expect them to win more than 5 of their other 9 games. That would give them around 8 or 9 wins and would not be enough to win the division.
Cowboys are better, have an easier schedule, have not played the Giants yet while the Eagles have already lost their home game against the Giants. Therefore the Cowboys constitute a much bigger threat to the Giants chances of winning the division. We want the Eagles to win this Sunday.