Sure, by definition: if a state's militia simply occupied a state fort which had not previously been used, or claimed, by the Federal Government, then that fort was not "seized", and no provocation of war happened.
But that's not what we are told happened, and so, giving you credit for accuracy, I'll assume what you say is true at least in some cases.
The question then becomes: in how many?
Remember, the total inventory of Federal properties seized by secessionists was not only old forts.
It included ships -- i.e., revenue cutters -- arsenals where weapons were produced and stored, and US mints where gold & silver were stored to produce coins.
I have seen lists of what all was seized and, other than possibly some old state forts, cannot imagine anything else as other than Federal property.
The rationalizing is incredible, isn’t it? It’s no different than going into your backyard and stealing your dirtbike. After all, you weren’t using it.