That isn't how it went down, Anders got fed up with Borland management and decided to finally accept the offers from ex-Borland folks to join Microsoft.
When he joined, his first project was being part of J++.
I have read that quite often here and there and while the management at Borland certainly was a pain, I don’t think that for Anders Hejlsberg this was the main reason to leave.
I believe (and I have no prove) that during development of Delphi V1.0 Anders realized that his „baby", the source code of the compiler core written in 16-bit assembly became worthless. The new 32-bit compiler for Delphi V2.0 was written in C by Peter Sollich.
Anders new role at Borland was just to be an architect / manager / teamleader / whatever… He could have contributed to the new 32-bit compiler in a way he does today to TypeScript, but for whatever reason he didn’t wanted to. That, along with the Borland management and the nice $$$ signing bonus offered at Microsoft made him leave. Again, that's just my take.
Peter Sollich left Borland I think in 1998 in order to join Microsoft, to this day he is in the C#/.net team.
https://youtu.be/LPcjSdob9AA
And I still wonder who has written Turbo Pascal for Mac in 1985/86…
