There was no fire, but there were most assuredly damages. Also, the only way to know the MC was not in the mansion when the sprinklers went off would be to have seen him dashing out of the house the instant before they went off. That's not exactly helping the MC's case.
What Lucas could do to help the MC is to make Jill realize the Preps at large aren't howling for the the MC's blood; it's purely Tybalt pushing the matter. Jill should have realized this already, but her brain was in the shop for repairs last episode.
Remember, Derek had to climb up to the third floor to break into the mansion, and we know Ashley was looking after the HOTs' bags on the third floor. I'm guessing Derek saw her and she gave him the cold shoulder, then broke down crying after Derek left.
At best we'll get an update on the current static render count; I will be surprised if DPC will even be ready to give us a total goal, but that is theoretically possible.
First, Tybalt can easily claim he was mistaken about there being a fire; the sprinklers were properly triggered, after all. Second, you're ignoring the possibility that Tybalt has money at his own disposal without needing to go to daddy first. Given how often he throws it around, that actually seems quite possible.
Now Stephen could probably make it hard for Tybalt to use it for an investigation, but that risks Tybalt wondering why. It's just as likely that Stephen would wind up finding the investigation himself just to keep personal control over what was found; whether that would be better for the MC or not is hard to say.
In short, I think your friends are thinking like the MC's attorney should, which would be fine if the MC were in a position to avoid their services. He is not. That means he needs ironclad proof that someone else was responsible (unfortunately impossible in this case) or a complete lack of evidence against him (when there's actually considerable circumstantial evidence that he was involved).
The disparity of resources in this case is so great that even a war of attrition in the MC's favor is likely to end badly.
