This word, I do not think it means what you think it means. Sampling is taking a portion of a sound recording and playing it within your own song. And even that, now, would require permission from the original artist, as the last major sampling case (Bridgeport Music, Inc. et. al. vs. Dimension Films et. al) found that "no substantial similarity or de minimis inquiry should be undertaken at all when the defendant has not disputed that it digitally sampled a copyrighted sound recording", meaning that, in that specific case, that the repeated use of 3 notes, lasting 2 seconds sampled from another artist did not fall under fair use. The part in question here is much long than 2 notes and 2 seconds, and would therefore almost certainly be found to be illegal.
But in any case, this is not about sampling - the court treats sound recordings (samples) much differently than the underlying compositions of the song. I would say this is almost certainly plagiarized, as both the melody, the chord progression and even the timing fits together perfectly between the two songs - but I doubt the court will award it in his favor, as not only will he be able to prove that the music is almost exactly the same, he will also have to prove that Coldplay had actually heard the song before, which would be very, very difficult.
[EDIT - Oh man, you were saying that the other 'riffs' that coldplay stole were actually just samples - not that the issue at hand has anything to do with sampling. God damn it late night, why do you have to make me misunderstand people]
