On the contrary, they benefit because a lot of investment is waiting for the true value of birr to be realized. It is no use making money in birr and you can't get dollars out of the country.

In the long term it will be a positive.
In the short term being that saf Ethiopia is highly indebted in Birr won't they have a hyper inflationary gain thing?
Don't forget IFC is invested in saf Ethiopia and is looking to lend them a couple of tens of Billions KES (in USD of course), they'd favor and influence for a system that makes it easy for saf Ethiopia to pay them back and receive dividends in future.
For saf it pays to have friends/share holders in high places.

Not really.
KCB and Co-op venture in SS wasn't debt funded.