That sounds quite naive to me 
Liverpool is already qualified for the next round and they can't be displaced from the first position as they are ahead with 4 points. Union Saint-Gilloise is still in the competition for the next round, but they have to beat Liverpool and then there is a slight chance they can still make it into the next round.
That's why I think this game won't be an easy walkover for Liverpool at all. I am sure that Klopp won't want to risk any of his players to get an injury and miss Premier League games.
I believe that tonight's game will be an easy win for Liverpool as they are stronger than their opponent so this will be a work over match. Liverpool stands a better chance to win this season Europa league and I don't see any club that can stop them, if they don't lose form. Bayern Leverkusen is also strong and I will love it if both clubs with clash in the finals to mate it more interesting. Liverpool is already qualified for the next round and they can't be displaced from the first position as they are ahead with 4 points. Union Saint-Gilloise is still in the competition for the next round, but they have to beat Liverpool and then there is a slight chance they can still make it into the next round. That's why I think this game won't be an easy walkover for Liverpool at all. I am sure that Klopp won't want to risk any of his players to get an injury and miss Premier League games.
You have been wrong here
As I said there was nothing at stake for Liverpool and still something at stake for Union Saint-Gilloise and they did what they had to in order to retain the chance to progress to the next round. But since the other game ended with a win for Toulouse, Union Saint-Gilloise efforts were wnot crowned with success. But for the future I think it should be paid attention to what is on the line for the clubs and it is not an exception that the favorite on paper loses the game because there is nothing to fight for. Since now some teams from the Champions League have also joined the Europa League, I am looking forward to the drawing for the round of 16.