While the question whether there were WMDs in Iraq is entirely separate from who was responsible for the anthrax mailings, it is worth noting that Al-Timimi’s charity was funding large sums of money to Iraq to help establish a caliphate there in Northern Iraq. The one friend of Ali’s I mentioned was sentenced to 22 years. Although not a subject of the charges, the sentencing memo explains he was funding the group renamed Ansar Al-Islam.
In a separate case, it was revealed that correspondence shows that Mullah Krekar, expected this charity person to establish a US center for Mullah Krekar.
So the responsibility of US-based Salafists opposed to the invasion of both Afghanistan and Iraq is actually entirely consistent with the prudence of vaccination (assuming for the sake of argument that it is safe).
Of course, resolution of Amerithrax would have helped ensure the safety of troops also.
But these Salafists were supporters of men like Azzam and Hekmatyar. Abiding by the teaching of Qutb and Ibn Tamiyah. They were opposed to Saddam because they considered him apostate. Having said, Saddam very likely had infiltrated Ansar al-Islam (through a fellow named Wael).
More broadly, more often than not, possession of WMDs is a reason not to attack them — not a reason to attack them.