I'll have to see if I can figure out a soulution to this kind of ask. It's been asked in a few different way over time.
The Requester / Provider station type is really not an actual state of the station. LTN does not differentiate between stations. If a depot signal is input, they are a depot only - no provide or request. If an item signal is input negative it will advertise a request, if an item signal is positive it will advertise an available supply. So every station can request and supply materials.
As such, the negative number from the combinator and the positive number taken from the storage are summed. The net value is then input into the station. If still negative, more is requested, if positive it is advertised as supply.
This is where the thresholds come into play. Setting the provide and request thresholds suppress advertizing requests and supplies if the absolute value of the net does not meet the threshold.
The idea of haveing a station be only a "Requestor" is implementd by createing a supply threshold so high that it won't advertise a supply. It does not change anything about the stop otherwise.
The Requestor / Provider checkboxes mostly determine which panels in the combinator will be shown. The will trigger the addtion and removal of the high provide threshold as that is the intent when manually toggleing the checkboxes. Otherwise, the checkboxes are populated when the combinator is opened based on the signals the combinator has set.
...Although as I'm typing this all out I have come up with an idea...
By setting a high Request threshold it will effectively stop all requests. So I may migrate the concpet of Requester and Provider stations back to a more genearic but provide a facility to disable and enable requests and provides by way of high thresholds.
Give a few days and I'll see what I can make work.
