Microsoft thought Linux as a new interloper, who was stealing away the Desktop market.
One who interlopes; one who unlawfully intrudes upon a property, a station, or an office; one who interferes wrongfully or officiously
disapproval If you describe someone as an interloper, you mean that they have come into a situation or a place where they are not wanted or do not belong. She had no wish to share her father with any outsider and regarded us as interlopers. = intruder. someone who enters a place or group where they should not be (inter- + -loper (perhaps from hleapan or lopen ))