Hylomar is supposed to be a 'none setting' sealant, and certainly it doesn't set rock hard like Green Hermatite for instance. However I suspect over time it will set hard enough to pull a cork gasket apart on removal.
It's certainly a very good sealant. I recently had a problem with leaking cooling hoses on my 100kW Induction Furnace - no matter how well or often I tried to make the copper pipe to neoprene tube joints leak free, they always wept a bit. So I disassembled them, smeared the copper with the Blue Hylomar out of my Healey tool roll, and slide the neoprene tubes back. Not a trace of problems since.
Wasn't there some talk recently about Hylomar changing it's formulation? On the strength of that I laid in a stock of a few tubes from eBay.