Steenhuizen is SABC News At the presidential inauguration ceremony at the Union Buildings in Pretoria.
The DA joined the ANC as well as other parties such as the Inkatha Freedom Party (IFP), the Patriotic Alliance (PA) and the Azania Pan African Congress (PAC).
According to Steenhausen, “it would be a sad day” if an anti-constitutional party such as MK had run the country.
“The real (problem) is with the anti-constitutionalists who are now hurling stones at the GNU, a party that campaigned on a platform of abolishing the constitution, eliminating the rule of law in South Africa, weakening the courts and eradicating private property in the country.”
He added: “That's why it was so important for the centre to come together to keep the anti-constitutionalists out of power. South Africa would be in a very different situation if the democratic centralists had the foresight to reach out, find each other, and bring parties like MK into the Union Buildings and stop them from wreaking havoc on our economy and our economic structure.”
The GNU is expected to resume talks on forming a cabinet after President Ramaphosa takes office, and ANC secretary-general Fikile Mbalula has previously said the GNU would hold inclusive dialogue with various stakeholders.
Video | Steenhuisen presents DA's position on GNU negotiations: