Nos 2 can be landed against poor-SDI opponents IMMEDIATELY after a correct range arcfire/arcthunder, or after SDI-ing out of a multi-hit jab if the opponent doesn't respond quickly. (These do not work with Nos 1/3) You can also use it as a very high-risk away-roll punish. That's about it.
The added value of a grab is non-existent on a move that can be responded to on reaction, because the entire value of a grab is bypassing shields--which can be acted out of immediately. Nosfertu is useless in the neutral.
Additionally, the reward for this incredibly difficult to land move is super low in 1v1 against anyone who can mash out. We're talking only a few %, with trivial healing.
Contrast with Ganon side-b 1, another very slow (also frame 16) move. Flame Choke has a massively higher reward unaffected by button mashing, almost always converting to at least 25% (d-tilt followup) which kills at ~110%. It can also tech chase for higher reward, and serves as an aerial approach tool.
More importantly, Flame Choke beats ALL of the following due to the snapback and wide area covered:
- Slow-reaction shield
- Spot Dodge
- Defensive tilts
- Away-Roll
- Some standard grabs
It also is relatively safe to inward-roll, usually only risking a dash attack.
Nos 1 only beats the first 2, while only giving a reward inferior to his normal moveset options (including grab).
Nos 2 only beats away-roll, at an even lower reward.
Nos 3 only beats spot dodge and defensive tilts, and only sometimes due to its inferior speed. The reward is still low, probably less than Nos 1 honestly.
In any case, the other opponent options (including inward-roll) allow f-smash levels of punishment.
It's just a terrible 1v1 proposition. In teams though, Nos 2 becomes safe (you have a teammate in front of you), easy to land (your teammate is pressuring them), and offers an high reward (your teammate's f-smash).
Nos 1 might work as an aerial mixup if they are just reeeally expecting you to fair into their shield for some reason. Nos 3 is too slow for this purpose, you can't surprise a shielding opponent with a ~30 frame move.