Is SCTP compliant to RFC4960#6.2 where it acknowledges on drop of DATA chunk?

Issue

• RFC-4960 Chapter 6.2 part states the following:

6.2.  Acknowledgement on Reception of DATA Chunks
   The SCTP endpoint MUST always acknowledge the reception of each valid
   DATA chunk when the DATA chunk received is inside its receive window.

   When the receiver's advertised window is 0, the receiver MUST drop
   any new incoming DATA chunk with a TSN larger than the largest TSN
   received so far.  If the new incoming DATA chunk holds a TSN value
   less than the largest TSN received so far, then the receiver SHOULD
   drop the largest TSN held for reordering and accept the new incoming
   DATA chunk.  In either case, if such a DATA chunk is dropped, the
   receiver MUST immediately send back a SACK with the current receive
   window showing only DATA chunks received and accepted so far.  The
   dropped DATA chunk(s) MUST NOT be included in the SACK, as they were
   not accepted.

• According to a wireshark pcap file it looks that it is not compliant to the RFC