I love this game I do and maybe Not everyone is a detective... but come on-
"Why would anybody do this to Billy"
"I dunno he's such a sweet guy"
"I just have no idea what so ever"
There's literally been a guy after that building for 6 episodes before this- thats THE ENTIRE PLOT
Gee I wonder who could have tried to have the building burned down????
Although you seem to be missing at least one important point that the characters themselves (especially Riley) have made. There have been several other businesses also in Midtown whose owners refused to sell, and none of them were targeted and bombed. I think the immediate suspect would definitely be Sharp or Daniel, but it doesn't add up. There would be other, less public ways of applying force. Daniel could be
stupid enough to do that maybe, but I don't believe he has the
backbone. I also don't think Sharp would want to draw any attention to himself. Since Daniel is his intern, it's not rocket science to connect the dots. This seems too sloppy for someone as smart as Sharp, and Daniel would never act on his own: he's a total yes-man.
Now, were this real life, it very possibly could be as simple as this, because RL people generally tend not to be that wise when committing crimes. (That's why serial criminals — arsonists, rapists, killers, whatever — tend to be even more shocking than those guilty of single acts. Skilled planning and frequent repetitions of the same crimes without being caught are much more rare.) But since this is a story with a plotted mystery, I would assume VW has made this more complicated than RL tends to be, like many other mystery writers. I would guess there is more to this than the obvious. If it's not, I will be a bit let down TBH. (I'll still like the game overall, but the mystery part would be a little disappointing.)