Why would he sign with PBC when no offer has been made from Tanks' team and they've openly talked about how they don't want the fight right now.

Or any Shakur fight. Walking him down with a high guard is the worse thing you can do against him.

Hearn already said he would step aside if Tank vs Shakur was being offered. It doesn't even affect the possibility of the fight happening. It'll happen when Tank's team decides to send an offer.

No they wouldn't. To begin with a promoter cannot ensure a fight. Secondly why would Al Haymon give his biggest cash cow to a fighter that doesn't sell half as much.

Dude do you even know what you're talking about. A promoter cannot force a fighter to fight another fighter of their choosing. Fighters need to accept or decline the fights that are offered to them. What Bob could do for example would be to tell a champion if you fight Lomachenko we can only offer you 500,000 while if you fight X we can only offer you 100,000 or whatever their contractual minimum payment is. Al Haymon legally can not promise a Tank fight because ultimately it is up to Tank whether he even accepts the fight. An example of this was Frank Martin's team calling off the Shakur purse bid because they thought they had a deal and then Frank Martin rejected and personally asked Shakur for more money.

You realise there's politics between promoters because of money not because they don't like talking to each other. A promoter does what makes the most financial sense for themselves. Which is why big fights can be made between promotions. Why would Al Haymon push for a Tank vs Shakur fight that makes financially no sense for him. He doesn't promote fights for our enjoyment. What you said about Crawford isn't even true to begin with. His lawsuit was regarding an accusation of racism in Top Rank and also because Bob never sent an offer to make the Spence fight. He was never in "purgatory".

Being promised a fast track route to a title is very different to promising a fighter. It is illegal for any promoter to promise a fighter to another fighter.

Why would the Shakur fight make sense for Tank at the moment? Every promoter does what makes them the most money. Tank will make a bit more than what he makes fighting a B level fighter while having a massive risk of losing and derailing his career. It's like Spence vs Crawford but in this case Tank is even more popular than Spence and Shakur is even less popular Crawford. And for Spence vs Crawford to even get made Spence had to push for the fight and make concessions that Al Haymon did not want to make. Shakur vs Tank is pretty much the worst thing Haymon can do from his perspective.