So far as the legalities are concerned, microlights are firmly limited to VMC, so it sounds rather as if this chap (or chappess!) was being a bit daft. With nothing equivalent to an AI, flight in IMC is very dangerous - the easiest way to kill yourself in a flexwing is to roll inverted.
As to the handling, the nature of a flexwing (which I presume it was if you identified it as a microlight from a distance) is that it will take quite horrendous turbulence - certainly with a good pilot it will handle as bad turbulence as most light aircraft. It is a rather exhausting experience, but survivable.
However, the other great attribute of a microlight is the ability to land in a tiny field. Personally, I'd have done so, preferably next to a pub, and gone home the next day.
G