I cant remember the timings. Was the suggested Weidman fight not leaving enough time to cut? If that's the case, then even the claim that he ducked Weidman carries no weight.
Silva ducks no man. But he's sure as hell gonna troll a few.
Here's all the background on the event I could grab from Wikipedia. Note that UFC 153 took place on October 13th, leaving Silva a month to prepare from when he took the fight.
Vitor Belfort was expected to face Alan Belcher at the event. However, Belfort was pulled from the bout to face Light Heavyweight Champion Jon Jones on September 22, 2012 at UFC 152. Belcher also was forced to drop out of the card due to a spinal fracture.
After having their first fight end in a no contest due to an eye poke in the first round, a rematch between Phil Davis and Wagner Prado was briefly linked to UFC on FX: Browne vs. Bigfoot and then scheduled for this event.
Quinton Jackson was scheduled to face Glover Teixeira at the event. However, Jackson pulled out of the bout citing an injury, and was replaced by Fabio Maldonado. Former UFC Light Heavyweight Champion Rashad Evans was offered the fight with Teixeira but turned it down due to the short notice.
Geronimo dos Santos was scheduled to fight Gabriel Gonzaga at this event. However, dos Santos pulled out of the bout after a blood test showed that he had antibodies for Hepatitis B. With no time to find a suitable replacement, Gonzaga was pulled from the card.
Erik Koch was expected to face UFC Featherweight Champion Josť Aldo in a title fight at this event, but on August 31, 2012, Koch was forced to pull out due to injury. Former UFC Lightweight Champion Frankie Edgar had agreed to step in for Koch and fight Aldo for the Featherweight title. However, on September 11, Aldo was also forced to pull out of the event with a foot injury after being involved in a motorcycle accident.
On September 12, 2012, UFC officials announced that UFC Middleweight Champion Anderson Silva and former The Ultimate Fighter star Stephan Bonnar would fight in the main event. Silva was a massive favorite going into the bout, which was a three-round fight. Although all main event fights have been five-round affairs since UFC 138, UFC 153 was the exception due to the short notice. On November 4, 2012, both Bonnar and Herman were revealed to have tested positive for banned substances, with Bonnar showing steroids in his tests and Herman for marijuana.
So the way I see it - he stepped up to save a BADLY stricken card. Having already lost Rampage, Vitor and an Aldo title-defence.