I see this is the main problem from complainers and crybabies, ''wHy hE bEggEd fOr hIs liFe''. He didn't.
There are more than 1 reason why Oda chose to do that. And I can't say Oda was wrong.
1- If Teach tanked WB's attacks with moderate effort like he did, and killed WB like a little bitch without that part, how would that look for WB? Oda needed to give something to WB fans and to WB for his respect for WB and at the same time Oda needed to make Teach the winner and also the killer of WB, and Teach was also going to toy with WB's corpse thats
too brutal:
Remember Oda brought Shanks to retrive WB's corpse as well not just stop the war. And Marines even told Shanks no, and they wanted WB's corpse until Sengoku said it doesn't matter.
Oda had little time in MF battle, he couldn't make a long battle with WB vs BB, so he chose to do that, made Teach the winner in short time, and also gave something to WB and his fans before making Teach killing WB like a little bitch.
2- Teach's relationship with WB is different. He literally says he trully respected and wanted to be like him just before their final battle, he still called him ''oyaji'' there, don't compare this with other fights. Oda also made it sure that there is no relationship left between those 2 and WB would never forgive Teach, otherwise people could blame WB for the things that Teach is going to do in the future.
3- Teach is
tricky, he was also trying to distract WB again by acting like he was still his son and attack him right after, he could call his crew earlier instead of that but he didn't.
Also Teach knew he wouldn't die from that attack as he draw his pistol and shoot WB right after in the next page, he didn't even lose his conscious like Akainu did, it makes no sense why Teach would think he would die from WB's attack even if you think he was afraid of dying, or you think Teach didn't realize his own superior durability and stamina for some weird reason despite being an observation Haki user.
If Teach was afraid of dying he wouldn't even try stealing 2nd DF knowing that he could die while trying, see how Jabra was scared of possibility of accidently eating 2nd DF and die.
And if he was scared Teach wouldn't recruit the most dangerous and unreliable level 6 pirates who can backstab him in any moment.
Teach would just rely on his
Warlord title protection, similar to Doflamingo or Mihawk and not leave the Warlords, instead of fighting the half of all Marines in Marineford Battle.
Oda is clearly not trying to show that Teach is afraid of dying, as he make Teach doing crazy dangerous things that no other pirate is doing.