In Tafsire Asr (Chapter 103 of the Holy Quran) Ali Muhammad Shirazi writes 'Surely unless someone harms him (Imam Mahdi), may my soul be sacrificed for him, his body will not be harmed in this world. This is because his body is completely secured (from dangers). And that is why the Hujjat (of Allah) peace be on him is alive and the numerous affairs (and events) of the world do not influence his body. And unless someone harms him, may my soul be sacrificed for him, the prolonged days will not have any influence on him (his body).'

Conclusion
Here are some deductions from the above statement of the Bab:

1. Bab reiterates that Imam Mahdi is alive till date.
   
   

2. The reason why Imam Mahdi is alive is because his body is made secure by Allah from all dangers. Even if someone somehow reaches him and tries to harm him, he will be unsuccessful in doing so. This obviously did not prove true for Bab when the government arrested him several times over leading him to repeatedly retract his claims. It is apparent that while Bab was right about Imam Mahdi's physical strength, he had grossly overestimated his own.
   
   

3. Again, as in Confession 3, Bab calls Imam Mahdi as the Hujjat.
   
   

4. Bab several times expresses his desire to sacrifice his soul for Imam Mahdi. If Bab is indeed the spirit of Imam Mahdi as the Bahais claim it puts Bab in the rather interesting position of sacrificing his own soul for his own spirit/soul. That does not sound like a very sacrificing individual at all. In fact it makes Bab extremely selfish; anyone who would sacrifice his own soul for himself cannot be anything else.