Its not known for certain, but it is highly probable that a delta instruction sequence larger than the max size will result in an result object larger than the max size. An evil user could create a delta instruction sequence that produced a smaller result than the delta is, which is evil, but isn't that harmful to the server. A more typical user would only use a delta sequence if it was smaller than the result object, as generally a delta is only chosen if the delta can copy more data from the base object than the delta needs to insert or needs to represent the copy ranges.

So, yes, if a delta was bigger than your limit, its pretty certain the result will be too big to accept.