He probably just signed his qualifying offer. $700K is the minimum qualifying offer for players 26 years old or older or they're free to sign anywhere. I'd imagine that a good chunk of the $750K he was reported to have made last season was a roster bonus rather than base salary. His base salary was probably "only" $550-600K.
I would hope that the Sabres are scouring the Group II list to see if there's any guys in that 26 year old or older group who were qualified less than $700K. They can be signed without any compensation. Joel Bouchard is probably in that group.
The Sabres official website needs to take it's cue from the Buffalo Bills. When the Bills sign a player they don't waste any time posting the news.