Well, the man came out and said it himself

https://www.washingtonpost.com/business/2020/08/12/postal-se...

Sure, I agree that Trump appears to be signalling that he is attempting to prevent mail in ballots from being delivered but it's really hard to picture how this strategy helps him? IE, I'm struggling to put together some sort of specuative game theory about the election that leads to him being president again.

You're right in so far as there's no direct supporting evidence. However, let's put a few things together:

1: May 6th, Trump appointee Louis DeJoy confirmed as Postmaster General and CEO.

2: June 30, Trump suggests that mail-in voting is fraudulent and suggests delaying the election because of it https://twitter.com/realDonaldTrump/status/12888181603895582...

3: July 15, DeJoy starts cutting costs and overtime during one of the most trying times the USPS has ever seen, resulting in delays: https://apnews.com/59c25efd4d325c4895f8ba85517f9bfd

4: August 7, DeJoy fires or reassigns 23 top executives, dramatically changing the existing power structure and centralizing decision making at the top. https://www.fastcompany.com/90538378/whats-happening-with-th...

No, those executives don't deliver mail. They did make all the decisions about how mail is delivered, who does it, and when. By centralizing the power structure DeJoy has put himself in the position of being able to make arbitrary decisions about postal delivery with very little immediate oversight.

The USPS is playing an unusually large role in this election and Trump (and, let's not forget, state-level actors that continue to take active measures in US elections) has indicated that he's open to messing with mail delivery to win.