Yes, you have stated the logical case but Zimbabwe is on the the...

Yes, you have stated the logical case but Zimbabwe is on the the wrong side of history when it comes to normal investors investing their money because of the past ,amply proven, risk to investing huge sums of money in Zimbabwe. So fund owners/managers like myself will be looking to make sure there are absolutely no legal loopholes that have not been missed in their due diligence. A fund manager such as myself would never recommend any investment of funds in Zimbabwe until all the required legalities are signed off. If they are not, and something goes wrong because I failed to carry out the necessary DD then the investor will certainly come after me and my assets to make good his own losses and I would lose my entire business reputation and deservedly so. My cost of doing business is heavy with insurance costs to protect myself but I am not aware of any reputable Insurer that will pay any claim if they find that I had not conducted proper due diligence.
The world's largest insurers are where huge chunks of investment funds come from and they have very sophisicated audit systems to assess investment opportunities.An unsigned PPSA is a very large red flag.

Of course, IVZ may be lucky and find a wealthy investor who will take this risk and go ahead without the signed PPSA.