We're kind of skeptical because if Hezbollah wanted chemical and biological weapons, they'd just get them from Syria. But he's Walid Phares and we're not, so here you go:

Mugniyah's death will be a significant blow to Hezbollah’s international operations. Analysts believe that Mugniyah was responsible for overseeing the terrorist group’s international operations, including its groups across the globe. Moreover, one of my sources in Lebanon said yesterday that he believed Mugniyah was overseeing the development of chemical and biological weapons for Hezbollah. Thus, the loss of such a central figure will surely be a blow. As an indication of Mugniyah’s prominence, the ransom for his arrest was higher than Hezbollah secretary-general Sayyid Nasrallah.

On the other hand, it would follow Israel waiting until the last second when it comes to Iranian-Syrian-Hezbollah weapons of mass destruction. Begging the immediate question: did the State Department try to stop Israel from protecting itself and the US? Stop it again, we mean.

References:
* This Summer's War With Syria - Syria Aims Chemical And Biological Weapons At Israeli Cities, Complains That Israel Might Attack It To Prevent It From Launching Chemical And Biological Weapons [MR]
* Mughniyah's strike: A Benchmark in the Counter Terror War [CT Blog]
* Merkel To Putin: Iran Is Kind Of Crazy, Shouldn't Get Nukes (Plus: Yup, Operation Orchard Hit A Nuke Facility) [MR]
* Syria's Been Building Their Nuclear Reactor Since 2003 And The State Department Still Tried To Stop Israel From Taking It Out (Plus: Awesome IDF Bombing Raid Just Got Filled With Even More Awesome) [MR]

Previously:
* Assad: Give Us The Golan Or We Won't Pressure Israel To Give Jerusalem To The Palestinians
* Iran, Hamas, And Islamic Jihad Meet In Syria To Plan Mideast Turmoil
* Syria To Launch Bio-Weapons Against Jewish State If The US Attacks Iran