Reality said:
True or not, league rules require that teams put players on the injury list when they have any type of injury, even mild. Now, they could probably ***** the severity of the injury (probably, questionable, etc.) but I'm sure the league watches the injury reports and players who actually play to see if coaches show a pattern of abuse.
However, I've followed the Cowboys and NFC East for a long time now and I don't ever recall hearing this rumor. It sounds to me like someone may be remembering some sports writer's opinion from way back then as fact now.
-Reality
I can think of a few instances where Gibbs "fudged" the injury report, but probably more than half the teams do it to some extent.
If you doubt that this is a regular occurence throughtout the league, remember back to the Atl/NE game earlier in the year when Vick went from doubtful to probable because he practiced so well, yet all media members reported that he didn't practice that day.
Or even when Belichek was chastised for not reporting injuries and then listed 20 some players the next week.
If a team/coach thinks that they can somehow gain a competitive advantage playing with the list, the modest fine is a small price to pay.
The problem lies with the injury list to begin with. It's a subtle wink wink nod nod agreement between the NFL and Vegas. It works out great for the explosion of fantasy players, but it's been around alot longer than fantasy.