One Outsider,
I'm not certain the regulatory (sorry "office expert") terms cloud the issue at all. Air time is air time and flight time is flight time. Pretty simple. It may be context related, but the OP question was specific enough to justify using industry terms.
Also, it's only the Out and In times which are at the discretion of the airline (push back or start). The Off and On times are not discretionary as they immediately impact any maintenance items which are air time dependant.
I digress, as this is way off the original topic which is whether block to block is "flight time?" Yes it is.