Peace Hope,
The preceding text 'fatawalla anhum' in both verses you have mentioned captures a situation where one turns away from a set of people. Therefore, the sentiments of the messengers captured seem to be post event and would capture their after thoughts.
In my humble view, no one needs to be present to hear such after thoughts but it is useful to remember that not everyone from their communities were destroyed. Therefore, some may have heard the messenger's general sentiments expressed as disappointment for their people, though not quite a lamentation (fakayfa asa ala qawmin kafireen? - So how could I grieve for a people who are disbelievers? 7:93).
Saleh (pbuh) and the believers with him were saved (11:66. 27:53 and 41:18) - He was not alone in faith at the end of his mission as he had confirmed followers which is affirmed in verse 27:47.
God always saves the believers along with the messengers which has always been His way "Then we will deliver / save Our messengers and those who believe: Thus is it an obligation upon Us that We should deliver / save the believers!" (10:103)
I hope that helps, God willing.
Joseph.