The REAL obstacle to SPSS

The solution is hinted by my comment above - don't allow a government of
any kind to operate the SPS but instead give it to a for-profit
enterprise. Business guys won't let their expensive capital be used as
a weapon - no profit in it.
Please look up the history of the following for-profit enterprises. Each of them have engaged in heavy duty violence, up to and including invasion and genocide, for profit.

East India Company
Association Internationale Africaine
Union Pacific Railroad

Your assertion that a corporation that operated a SPS would not engage in violence (or the threat of violence) because it would not be profitable rests upon the assumption that violence would not be profitable. I don't believe this is necessarily a valid assumption.

Everything the company operating the SPS array does (or any vehicle in
orbit) is open to inspection by anyone with a good telescope on the
ground. This is your solution to the 'using X as a weapon' problem -
shenanigans like this will be seen and corrective action taken.
Against whom? By the time it's up there, it's too late.

I'll got a step further - any enterprise in the space access industry
might be advised to open their internal business up to public inspection
as far as they are legally allowed to. You can't do anything without a
paper trail, and this would include shipping to, and operating an
illegal laser cannon. If the public can see this happening, things can
happen to prevent it.
The technological history of Iraq indicates that this is an unlikely circumstance.

No, I'm not so far gone as to imagine you'd find an invoice for "1) Acme
X-Ray Laser" but the bits to assemble such would be visible if anyone is
looking.
Would they? I'm not convinced, and I don't think your average national leader would be either. We're talking about power (in the political sense) on a level unheard of in human history.