Hello Hebittue71
Yes, you are welcome to purchase the Saver Day Pass with or without the Swiss Half Fare Card. Saver Day Passes are available at half fare, as well as at full fare.
The Swiss Half Fare Card offers the same benefits as the resident’s Half Fare Card.
https://www.sbb.ch/en/tickets-offers/tickets/guests-abroad/swiss-halffare-card.html
The thread you are mentioning was about the Day Pass for two, which was initially not available for tourists. This was a temporary offer and has nothing in common with the Saver Day Pass.
https://www.sbb.ch/en/tickets-offers/tickets/day-passes/saver-day-pass.html
Save your passes as soon as possible as the price is increasing the nearer the travel date. However, be careful as they are not refundable in case of changes to travel plans. Also, as all e-tickets, passengers using a Saver Day Pass must show their physical passports upon ticket inspection.
Kind regards,
Roland