Tank sealant was chosen for two reasons -
To take advantage of its slightly flexible property's to account for skin drumming / vibration, and different expansion/contraction of the different materials.
I am sure other adhesives could work (there are many instances of aluminum being adhesive bonded on aircraft), but I am not personally aware of anyone using something else, and what the result was in long term service.
The very first Van's prototype to use the process was the prototype RV-9A. It is now has 2500 + flight hrs and 15+ years in service with no problems.
But, they are experimental aircraft. You can choose to use what ever process you want.