My $.02 worth.
Use the Vulcem or other sealant that works the same way.
The Silicone WILL NOT maintain the bond to the Aluminum so your repair will be short lived. Buy it in bulk and it will not cost that much more than the silicone would have.
Besides the Vulcem will stick better to the Old Vulcem than the Silicone will.
The mess you make will not be seen and the seal you apply could stop you from having to replace part of the floor. If it was mine I would reseal anything that looks questionable.
WBCCI #5501 AIR # 49
1978 Argosy 28 foot Motorhome
Wise men talk because they have something to say; fools, because they have to say something. -- Plato