As a former Union prop (loosehead) this is a must avoid game for Leeds. A union scrum is a highly developed set piece that doesn't just work its takes alot of effort and practice to perfect. Any Premiership team infact any national league team worth their salt should be able to screw Leeds into the ground at the scrum and be awarded constant penalties.
Even with the flankers dropped (usually the lightest) i'd expect the 6 man scrum for Leicester to be pushing 650kg. All they would need to do is drop the ball every few mins (like a normal game!) and just enjoy the scrum.