Having worked in restoring a number of these tubes over the years - I can say that once it's done - they find new use and they get shown off as prized possessions.
The state keeps them - partly because of the fact that no state wants to be seen to be getting rid of its heritage and no Guard outfit wants to rid itself of 'any' sort of fireable weapon.
'Sometimes' - the restorers can sign for them as a part of a display - but only for short times and under heavy security restrictions and high insurance, and they purposely keep it that way to discourage folks from trying to do it.
If 'rescued' - the likely rescuers will have strong ties to the state's museum system, and that's where it'll stay.
Currently - it should be on the books of the United States Property and Fiscal Officer, who's located at the Adjutant General's Office - wherever that complex might be.
He'll be a Colonel - but only on the part-time side - in reality, he'll be one of, if not 'the' highest-paid civilians in that workforce, and will have more 'actual' power than the TAG, since his job isn't political, and dependant on a Governor's whim.
It's not his job to let assets loose - and if interest's shown, it suddenly becomes an asset...
Now, if the unit's NCO Association were to build a concrete plinth to support it - it could be displayed proudly at the armory it's currently resting in.
At least more folks would see it than they do at the moment.
Scouts Out!