I pretty much expect it to happen now. Not sure why they ever left the GMC in the first place?
If I had to guess: football.
They were already associate members of the NWC from 1967 on, and then joined in all sports in 1974. Keep in mind in the GMC, Ayersville didn't start football until 1976. Holgate 77. The first year Tinora shows up in the OHSAA rankings is 74, so if they had a team it was JV level. That would have meant the GMC had 5 football teams at the time Paulding left.
My guess is, the NWC pushed them to decide on full membership or get out for football, and they took full membership. Had they stayed patient a couple of years, there's probably a good chance they stay. Although in either league for a long time they stuck out like a sore thumb enrollment wise, considering they were D3 in football as late as 1996 and were in D2 in basketball into the early 2000s (I remember a couple of Defiance-Paulding sectional games after Defiance fell out of D1).