Rovers appealed last night but saw the ban actually doubled to two games for the appeal’s “frivolous” nature.
It means Tomkins will miss Friday’s last game of the campaign at Salford - when they must win to avoid any threat of the drop - but also carry another match into pre-season.
“It seemed from the club perspective it was worth a try,” said Smith.
“But we’re going to miss him for the last game.
“It’s tough. It’s tough to understand some things sometimes.
“But we’ll accept it now and move on.”
Rovers also lost centre Jimmy Keinhorst (concussion) to injury in the first half of the costly defeat against London which left them level with Broncos, Huddersfield Giants and Wakefield Trinity on 20 points at the foot of the table.
However, Dean Hadley, who came off with a dislocated shoulder in that first period, is named in the 19-man squad and hopefully fit to resume.
Australian full-back Adam Quinlan and back-row George Lawler are due to return after various lay-offs and Australian centre Kane Linnett, who dropped out of the London game with a rib injury, is also back.
“Kane Linnett’s got a chance, and Quinny, too, while George Lawler could come back into it,” said Smith, with Danny Addy another option.
“We’ll assess them all tomorrow and see where we’re at then.
"We'll give them as long as we can to see if they'll be right.
"They need to be OK and there's a number of possibilities over the next 24 hours.
"People are always carrying niggles at this time of the year but it's looking quite positive."