Here's what he said anyway, for others who might wonder the same thing:
"I have unthinned VG-nic in well-sealed glass in the freezer that is virtually unchanged after 6.75 years. In plastic, especially LDPE, it will oxidize, even in the freezer. Some PG-nics I've had in glass did oxidize in the freezer after about a year, some didn't."
"I don't have data on frozen ready-to-vape e-liquids with flavors, since I make my own fresh as I need them. I don't buy flavored e-liquids, and I only freeze unflavored VG-nic, mostly 100 mg/mL."
"Cold slows all reactions down, frozen solid or not (VG does not freeze entirely). This is a function of chemical kinetics and molecular dynamics...nic and O2 cannot move well in the thick glue-like liquid that VG turns into in at freezer temps, so they don't find each other as easily."
"I have every reason to believe VG-nic will last essentially forever unchanged in the freezer and in glass. If 6.75 years shows no change, I don't see at all why it shouldn't last for decades."