Listen to Rand's half-hearted plea to Starfleet to abort transport. She
is obviously faking it. She DELIBERATELY screwed up the transporter
circuit in Engineering (she had 18 months to figure out how to do it) to
ensure that it would malfunction. Why would she do this, you ask?
In the novelization of Star Trek: The Motion Picture (I know it's not canonical
but it will serve my purposes), the other person transporting aboard was
Kirk's WIFE! Janice Rand has always been trying to get Kirk's attention
(it's very hard in those bland coverall uniforms) so she decided to get
rid of the competition. Why, then, didn't Rand go after Kirk when the
dirty deed was done? Guilt. Too little, too late, Janice!
And poor Sonak! An innocent pawn in the dangerous chess game of love.
Lol - yeah a clear case of Munchausen by proxy and these were the only two kills Janice got in her entire Starfleet career! Give her a break.
I don't think Rand can be blamed for the transporter malfunction. The transporters were offline before Scotty came on board so it must have been Scotty's decision to bring them online again (possibly on orders from Decker but Decker does seem to be the more cautious type). I agree, it's odd that they didn't test the system more before greenlighting the system for humanoid transport but they may have been testing the system all day to isolate the problem. Any car mechanic knows that intermittent faults can be hard to track down.
The problem may have arisen because removing a functional module, which would normally have worked as an additional back-up, placed greater strain on the faulty module. Since it was Scotty tinkering with the system DURING A TRANSPORT after authorising the system back online, I think the buck stops with him.
Now if Rand was contacted direct by Starfleet and personally approved the transport despite the system being officially offline then the buck would stop with her instead but requests would normally be sent via the comms officer and a direct request is never implied, as Kirk's comment to Rand suggests.
What is curious is that the error raises questions about safety procedures and the nature of transporting from one pad to another, which is meant to be safer than using just one pad. It may be that the fault occurred a fraction of a second after the Starfleet pad released the signal so it was a million to one accident.