Making sense of guarantor in the marlowe example

I’m reading Marlowe tutorial, specifically figure 5 in this page

It introduces a guarantor who deposit the whole loan amount upfront, which will be used to pay investor if issuer defaults. I find that is a little bit strange. Why does guarantor loan the money to issuer directly? Note guarantor is taking the same amount of risk as lending to the issuer while getting less reward (because part of interests go to investor)

This does not make sense to me. Or does it?

In traditional finance, a guarantor is the person who is obliged to pay the balance of the debt if the borrower defaults. In the case of bonds this is the party or asset covering the collateral for issuance. The investor and guarantor do not need to be the same entity. A third party guarantor mitigates some of the risk for the investor.

Of course this contract is a much simpler example than what you would do in reality. Often this would be leveraged at a discount of the face-value. In the case of zero-coupon the investor should make no money at all until the bond matures. The guarantor would likely have additional stipulations before providing the funds and both parties may not collect an even portion of the interest upon maturity.