I noticed the same thing. It is strange to have the prefix suggest an object that has a Type 5 suffix (except {-‘e’} because, hey, {-'e’} is soooo exceptional). It’s more typical to say {bIQtIqDaq jIghoS} or {bIQtIq vIghoS} than {bIQtIqDaq vIghoS}.
The object of the verb ghoS is the course being followed, possibly a course identified by its destination. That is, its object is already locative anyway, so there is no reason one couldn't add a -Daq to it. As TKD says, doing this is a little redundant, but not wrong. When a verb makes its object locative, adding the locative suffix doesn't change anything at all about the sentence.
And by the way, the gloss of ghoS also includes "go away from." I have no doubt that you could say things like bIQtIqvo' vIghoS I go away from the river. ghoS can impart an ablative meaning to its object instead of a locative meaning, so we should not be surprised if adding the ablative suffix to the object has no effect on the sentence besides being redundant.
This idea that objects should never have type 5 suffixes on them except for -'e' because it's exceptional and except for -Daq on certain verbs because the verbs are exceptional is a kludge made up by us, not Okrand. A more accurate "rule" would be that type 5 noun suffixes can go on any subject or object provided the verb supports locative/ablative/benefactive/causative/focus nouns in those positions. The role of focus is universal. A bunch of verbs support a locative object. A couple appear to support an ablative object. We know of none that support benefactive or causative objects or or any sort of subject other than a focus noun.
The rule is not that subjects and objects cannot take type 5
suffixes; the rule is that nouns that aren't subject or objects
come before the object and usually have type 5 suffixes. (Examples
of nouns that aren't subject or object and don't have type 5
suffixes are time expressions.) There is no prohibition on putting
type 5'd nouns on subjects or objects, and we're explicitly given
instances where -Daq (and now -vo') go on objects.
Sure, you can do it. It’s just weird, even if Okrand does it.
Only if you presume a rule that TKD doesn't actually state. This
is one of those "we made ourselves think this way" things.
One might expect a parallel between the use of {-Daq} with its special verbs and {-vo’} with its special verbs.
The verbs are only special in that their objects are locations. You ghoS a location because ghoS is all about acting upon a location, so it's really not surprising when you put the location marker on the location you ghoS.
-- SuStel http://trimboli.name