The thing is that Thunder is very reliant on rain to work, which HO teams often don't have the slot to use. Of 'course if you are facing Tentacruel its probably going to be on a rain team with rain already up, but using an unreliable move that hits reliably only one Pokemon (and generally hits only one Pokemon that Gengar really cares about) is probably worth more of AC that main slash. This said, however, this doesn't mean that Thunder + HP Ice won't get a big mention in AC, as i have used it and it is indeed very useful against rain teams.
HP Ice should be slashed over HP Fire at least speed ties are really important with that set and HP Ice catches so many things off guard like Garchomp, Dragonite, Gliscor, or LandoT, which makes Rak / Luke / Looms / Dnite / etc.'s job easier. (HP Fire should bump down to AC tbh).
Thunders acc is the same as FB's sure missing it sucks but most HO are coin tosses anyway what's one more? (Also you made EB a slash and EB / Sash work with the coverage attacks better in this meta than Destiny. DBond is more unreliable than Thunder js).
TBolt is not that great but should get AC as TBolt + SBall reliably beat Skarm.
While ia agree completely with shurt on the Hp ice > hp fire thingy, i think icy wind deserves a mayor mention in the ''D-Bond'' (even though we dont know if thats even going to be a staple in the set anymore) since it eases prediction in some plays, im not asking for a slash in the main moveset, but rather a simple mention of it and its pros in the AC of the set.