So from my digging, the only place I found any mention of a potential Austrian attack on Italy in the aftermath of the 1908 Messina Earthquake comes from Franz Conrad von Hotzendorf's memoirs, Aus meiner dienstzeit, Volume 3, where as chief of staff of the Austro-Hungarian army, he requested a surprise attack against Italy twice; once after the earthquake, and again during the Italo-Turkish War. Both were dismissed by the Austrian Emperor along with an implied mediation by German diplomats, advising against an Austro-Hungarian attack on both occasions.

Hotzendorf is a rather interesting military figure; brash, outspoken, deeply nationalistic, and sought to recover territory lost in the Italian wars of Unification, but his requests for war against Italy were never seriously considered by Emperor Franz Joseph. Namely, because Italy was a de facto ally of Austria-Hungary as both were members of the Triple Alliance with Germany. Austria-Hungary attacking their own ally at an opportunistic moment opened up by a natural disaster would be a diplomatically suicidal action to take. One that would certainly see intervention by the German Empire in support of Italy against Austro-Hungarian aggression, as well as permanently tarnish the diplomatic reputation and credibility of the Empire on the world stage.

Hotzendorf may have wanted war with Italy, and would eventually get it in 1915, but the Austrian Chief of Staff failed to take in the diplomatic backlash such an action would be met with, which would be faced with universal condemnation from both Germany and the other Great Powers of Europe for such an action.