Why, oh why, would the GMA administration cover-up the truth if it indeed was a bomb that caused the explosion? Wouldn't it be favorable to the then Gloria administration to claim it was a bomb rather than a gas leak? It could have been a good reason for her administration to crack down on her critics, but they did not do that.
But I think I know the reason behind this so-called "re-investigation". The Ayalas, who own Glorietta 2, are liable and subject to lawsuits for the explosion if it had been a gas leak, and they wouldn't want that to happen. Hey! They supported Penoy's campaign, so why can't they just have it re-investigated by their "boy" Penoy and have the new results "tweaked" to show that it was really a bomb and not a gas leak? I mean, the Palace go-boys have proven their skill in tweaking investigation reports.
I see no logic in the need for the past administration to cover up what happened in Glorietta 2... But hey, it's Penoy's Truth Commission, and they've been given a blank check.