The loan is for KLM, not those other companies. If any other company wants a similar arrangement they can expect similar condition, if it even would be considered.
That is not how the government sold it. They save KLM not because they want KLM to stay afloat, but because if KLM falls, numerous other companies fall too. They called KLM the "eerste dominosteen".
The law that limits taxpayer payed salaries already applies to air traffic controllers, thus the government limits their salaries already.
I know in fact what a senior ATC employee makes and that is way above the maximum for public companies.
And that norm is moot anyway, state aid, which is a loan, not a cash gift, doesn't give the recieving company the status as public company. Neither is it nationalised, so there is no lawfull basis to cap the salaries.
They applied it on themselves as well.
Excuse me if I am a little skeptical about that. Senior/higher management have a very complex pay structure and it wouldn't surprise me with a little creatieve book keeping this will not be same as the rest of the employees.
Of course, this is purely conjecture, but apperently the first internal memo has already been distributed stating almost the exact thing, that management payment is complex and whilemit might look like they won't give up 20%, they will surely do that.