Does the job title 弼马温 really signify 辟马瘟 'avoid horse fever' 猪八戒说，“你这个弼马温!" baidu.com: “弼马温”不过是辟马瘟的谐音而已。

Someone else told me, 弼马温 might really be 弼马翁。

弼马温 was 孙悟空's job in heaven. baidu.com here has: "这样能有效的趋避马瘟。"

"古人们在马厩中养猴子"

Was Sun Wu Kong's job really to agitate the horses to avoid them getting horse fever? Did the ancient Chinese really keep monkeys in their stables?
The ancient Chinese did keep monkey in their stables,

But they actually keep female monkeys, as they believe their menstruation can prevent horse fever (馬廄畜母猴辟馬瘟疫,逐月有天癸流草上,馬食之永無疾病矣)

By assigning Sun Wu Kong to a female monkey's title, it is probably a subtle joke from the author.