网友确实不该将这二个句子写在一起，给人感觉它们是相邻的二个句子。

其实，这二个would的用法并没有什么特殊，就是传统语法中的过去将来时，表示过去将来时间将发生的事件。

通常说话人在叙述过去的情况时，自己的思绪或随着对事件的描述而向时间轴的右方移动，即说话人描述的都是他关注的那个时间发生的事件，因此通常用一般过去时或过去进行时描述。当有时为了避免单调，说话人的思绪会停留在过去的某个时间点，将随后发生的事件用过去将来时描述。例如：

Mitchell, though, was struck by it and by the crowd that gathered the night after the raid, calling for gay power as another tense standoff developed with police.

Two years later, he would become Indiana University's first openly gay student senator and tell a student newspaper gay people were "showing that our power is real."

说话人的思绪（并且因此影响听话人思绪）停留在上句 calling for gay power as another tense standoff developed with police.这个时间节点。

对比：

Mitchell, though, was struck by it and by the crowd that gathered the night after the raid, calling for gay power as another tense standoff developed with police.

Two years later, he became Indiana University's first openly gay student senator and tell a student newspaper gay people were "showing that our power is real."

说话人的思绪已经 he became ... first gay student senator.这个时间节点。

二种描述相比较而言，第二种时态比较单调，给人以沉闷的感觉。第一种则显得灵活，更能引起听话人的注意。

...,so I assumed he just wanted to know why my vehicle had stopped amidst rush hour traffic.

What I did not expect was that, not very long later, he would reappear with a colleague and say they would be changing the tyre.

这段话中的would 则很简单，说话人当时没有预料到（用一般过去时）警察后来会做某件事。警察做某事是expected (或 not expected) 之后的将来的事，当然要用过去将来时了。

be to do表示将来，表示事件在将来的发生，是be那个时间节点的plan或arrangement，或者是命运的安排（命中注定会发生某事）。这不符合原文的语境。所以，用be to do解释would在这二个句子中的用法，是不大合适的。

以上为我的看法，仅供参考。