I'm also going to cut him some slack with the bit about giving each segment a unique number. While formally the sequence number identifies each byte of data, it really is about providing heuristics to identify and correct for out of order, fragmented, missing & duplicate segments. It is important that it be about bytes, particularly for things like SACK, but if you are trying to simplify things you might describe it as being about the segments.
Sure, nothing wrong with simplifying things, but "Both ends are sending sackOK. This will enable Selective Acknowledgement. It switches the sequence numbers and acknowledgment number to use byte range instead of TCP segment numbers." is just flat-out wrong, and in particular suggests that "numbered segments" is not a simplification but an actual fact about how the thing works.
