I think the real question that needs to be asked is why?
Why would ComStar opt for open conflict?
Until the Clans bluntly and directly claim Terra as their intended target ComStar hasn't been placed in a position where massed open conflict was necessary. I still don't see an assault on Luthien prompting such a response simply because better, more covert and more often used tools in ComStar's arsenal haven't been utilized first.
You gotta think like 3039 ComStar.
For one, they've never fought a pitched battle, or consolidated. The Guard has never really operated in large formations. ComStar has no real working industrial complex. (This is before the massive losses on Tukayyid, so most of Terra's factories are mothballed at this point.) Primary income for ComStar comes from their HPGs. Burning them would be akin to cutting their own throat. Abandoning the HPGs, or disabling the software should suffice. For one, operating the HPGs should be beyond the capability of everyone except Wolf's Dragoons, so its the technicians, and to a lesser extent, software that needs to be nullified...not the hardware. (For example, say ComStar did "win," they might have to replace all of those HPG sites. That's a ton of cash and resources. Outlay they'd have to provide after fighting a major war.)
But really, you have to return to the why? Why would ComStar go toe-to-toe with the Federated Commonwealth?
From a risk standpoint, open warfare prior to exhausting ComStar's other tools is paramount to suicide. Especially when you consider what an Interdiction, combined with a covert ROM war might accomplish instead. And these are operations directly against the Suns, and operations ComStar is intimately familiar with conducting. But honestly, when has ComStar ever relied solely on direct operations?...Before Scorpion, ComStar was all about pawns. Specifically, the other Successor States.
What if ComStar provided information, assets and other resources to the FWL & CC, or even the TC? Would they be able to entice them out of entropy? Perhaps, perhaps not, but its something ComStar would likely attempt prior to building a buffer state around Terra from the get go. Maybe ComStar will stage another performance act or two on a couple of FWL/CC worlds pointing fingers at the FedCom. It worked on Sarna in the Fourth after all.
The point is, ComStar's smart enough to exhaust what it's comfortable doing before opting to do something it's not when a final outcome, or direct threat is in doubt.
Now, if Hanse Davion declared his intention to reform the Star League after sacking Luthien by claiming Terra...while premature and possibly crazy, may earn him a response ComStar's not entirely comfortable doing, but shocked enough to use.
Say, like some sort of armed, or more overt resistance.