I think the native Russian speaker is automatically projected into a scene in a house where he or she has just put on slippers next to the closet and padded happily into the living room, commenting on the slippers he or she is wearing. So in the spirit of Russian mind-meld, "these" is better. But technically, "those" could be used.
google translate translates the adjective here as "удобны". This is called a short adjective I think which has no noun after it. There is also Masculine Feminine Neuter Plural Short Adjectives красив красива красиво красивы
a table like this on short adjectives on russianlessons.net.
what is the reason for this difference?