Bob's board: nothing (everything exiled to Teferi emblem already)
This game's effectively over: Alice wins eventually since she can continuously discard Nexus to hand size while Bob cannot keep a permanent in play. This means Bob will eventually lose to milling (see also Edits #1 and #2 about what Alice can do against any possible play Bob can make). But Bob refuses to concede. It could be for a variety of reasons, the most important of which is he won game 1, so if he can stall game 2 for long enough he can make sure he will at worst never lose the match. Meanwhile Alice cannot win faster; milling with Teferi emblem is her deck's win condition.
When confronted about it Bob says Alice needs to actually win the game in order to win the game, and while he's at it, he insists on shuffling Alice's deck every time she discards Nexus of Fate.
If we assume that Bob genuinely does not have a way to avoid losing eventually, is this kind of behavior punishable as time-wasting? He's not taking a long time to think, shuffle, etc - he's just refusing to concede.
Related: Can my opponent force me to play out a demonstrated loop? However in this case, Alice is passing the turn and not looping.
Edit: to clarify how the Nexus lock works, what happens is that you get Teferi to 9 loyalty, ultimate, and then start using its -3 on itself. This guarantees that you'll never run out of cards in your deck (you can also discard Nexus to hand size, since it shuffles back into your deck). Meanwhile you can cast Nexus as many times as necessary to exile all your opponent's permanents, including lands. If they put into play multiple permanents, you can simply loop Nexus, each time removing one of their permanents, so they'll never untap with any permanents in play.
Opponent can play a land and resolve a 1-mana spell, but that spell will have to do direct damage because otherwise any permanent will be exiled come the next turn. Haste creatures don't matter because Tamiyo can cast and recast Root Snare, which prevents their damage. That leaves 1-mana burn spells, but since the only legal 1-mana burn spell in Standard is Shock, 4 copies of this will still not be enough to kill Alice. Fanatical Firebrand can contribute another 4 damage, not enough either. The list in Edit #2 even includes Revitalize so burning Alice out is not an option (she can go to an arbitrarily high life total if she wishes).
In other words Bob is 100% to lose if the game goes on, regardless of what deck he's playing and even if he had access to every single Standard-legal card (except his own Nexus of Fate, which we assume is not in his deck). He's just refusing to concede until he actually loses.
Edit #2: can't believe how difficult it is to word this question. The format is Standard, and here's the list Alice is using. It is postboard and Alice has switched out Nissa for Veil of Summer because Bob is not playing a Nexus deck, which means she does not need a way to attack Bob to zero.
Alice effectively has infinite copies of any cards in her deck because of Tamiyo. How it works is, say she needs to cast the Revitalize in her graveyard, but Tamiyo does not have enough loyalty to use her -3 ability. She can cast Nexus of Fate (it shuffles back in), then tick up Tamiyo naming a card not in her deck (again, she will never deck herself because Nexus shuffles back in). Next turn she can repeat this, until Tamiyo has enough loyalty to tick down. In the same way she has infinite copies of Root Snare if she needs it, she can also tick Teferi up endlessly, and she can refill her hand to seven cards (so she can discard Nexus to hand size) if necessary.
Because there's no way to get out of the lock in Standard (if anyone can think of a way out of this lock, using any Standard-legal card other than Nexus of Fate, I would be interested in it) everyone knows Bob is 100% going to lose, including both Alice & Bob.