Nope. Missed a heartbeat means gone. We discuss churn later in the article.
Its effects are complicated, but as long as d holds, everything else holds.
Suppose we have a faulty node heart-beating correctly but not responding to proposals, or selectively responding to proposals.
This would seem to imply that dishonest nodes have full control over which decisions are made.
I still have doubts that you can handle a dropped message or how much control a faulty node has over decisions, but I'll leave that to you to work out.