Sidwell, who was given a straight red for a dangerous tackle on QPR defender Armand Traore three weeks ago, caught Mikel Arteta on his standing foot with a two-footed lunge just 12 minutes in to this afternoon's London derby at Craven Cottage.
The Gunners boss had no qualms with Giroud's sending off, and that of Sidwell, which he thinks could have caused serious injury to Arteta had it happened a millisecond earlier.
"I think the referee could only give a red card (to Sidwell)," the Arsenal manager said. "We will see (if Arteta is Okay). He played the second-half. I don't know how much damage is done. It is a kick, a bad kick.
"I don't know if he has twisted his ankle or not. In these kind of things it is a question of a fraction of a second.
"If you are fully on your foot at the moment you get it you break your leg. If you ease a bit off maybe that is why he got away with it."
Sidwell's tackle on Traore - a long sliding lunge while the Frenchman was at full pace, drew widespread condemnation, and the former Chelsea man can have no complaints about his dismissal on Saturday.
Fulham boss Martin Jol admitted the 30-year-old, who has also been booked eight times this season, deserved to go.
"I can't defend him because that would only sound ridiculous," Jol said.
"I was annoyed with him, but he says it is not intentional. He will regret that tackle. It was the first foul that spoilt the game.
"I know it was not intentional because he wanted to play. He has just come back from a three-match suspension and now he is out for another four matches again so it was not only disappointing him, but also for us because we had to play with 10 men for a long time so that was more disappointing."