I see the same thing, so perhaps do a double and triple check? Lets do some digging...

Not that they know everything, but when in doubt, I also double check with parts suppliers. E.g. this one states explicitly: "Volvo 200, 300, 700, 900 with B200- or B230- Engine: The outlet valves have no stem seals, required quantity 4 pcs for one engine."

That probably means that at some point in the past your B230FT already had work done and someone installed the seals on all valves.

I can understand the confusion, if the rebuild manual doesn't specifically state them, it is easy to assume they go on all valves.

If I look at the overhaul procedures in the Haynes manual (200-series), it also doesn't state the number of seals used, but it does show a drawing pointing out the differences between an early type and a later type seal.
That drawing shows an inlet and outlet valve with the inlet valve clearly identified. Only this valve has the seal in the drawing.

Back to the source, Volvo. The drawing below shows part #17 to be 1306630, the valve stem seal. If you scroll down to part# 17, it lists all compatible engines ending with the word "intake".