The acetone sounds dodgy to me but it might work for different reasons. Rot
I do know a bit about from my early days with wooden boats although I'm
remembering back a quarter century.

Rot is a fungus that thrives within a very narrow range of moisture
conditions. Water alone doesn't rot wood although it might break down bonds
between balsa and fiberglass when aided by the impact of feet. Acetone
fumes might kill or slow down the fungus although I've never heard such a
thing. It might also accelerate the separation of balsa and fiberglass
which would make the decks spongy.

When conditions are right, rot can move with incredible speed, up to 3/8
inch per day. The rest of the time, it goes into spores and lies dormant.
Moisture gradients and areas where the conditions get wet and then dry out
create zones where conditions are perfect. An unbedded fitting where the
core is wet and then fades out to dry is such a place. Having new rain
water coming in at the leak, along with spores blowing in the wind, and then
drying out slightly also can take the wood through optimum conditions.
Getting the deck sealed up so everything is stable might therefore stop or
significantly slow the degredation even if water is present. However, if
the moisture range is just right and stabilized, the whole core could go
quickly.

I wouldn't just rebed hardware but open up the mounting holes a bit and use
the trick of an "L" shaped rod chucked into a drill to rip out as much core
as possible. This will remove the stuff most likely to contain spores and
aid drying. Suck out the sawdust with a strong vacuum and pour in an epoxy
with good penetrating power after drying as long as possible. Replacing the
core with solid epoxy between the laminations will strengthen the fittings
and tie the skins together in a way that will help strains prevent
separation of glass and core.

On the bright side, the upper skin of the deck in a boat of your age is
probably as thick as the deck of an uncored boat would be if built today.
Even if some rot and a bit of deck flexing are present or do develop, she
will still be strong enough for anything you want to do with her except get
you purchase price back.

--
Roger Long