However I would put forward that if whoever spoke to you on the radio could not guarantee there was no traffic in the circuit then the correct thing to do is ask for an ohj so that you can assess the traffic situation yourself.
Sure, that was an instructor who was doing that stunt, not a "tower employee".
I don't see a basis for an OHJ being the safest approach, however. It is often touted as such, but this is only if you are the only one up there at 2000ft AGL. Normally, with an OHJ at a busy place, there will be several planes doing the OHJ at the same time, and you will never see some of the others. But all are at
your height... and they can't see you either. It's not so smart.
I think the OHJ dates back to pre-radio days when the pilot would circle, examining the signals square. And the days when there was no concept of accurate navigation, so navigating to a point representing the extended runway centreline say 5nm away (routinely done with a GPS) was not possible.
But if you are going straight in, say after setting oneself up at 1000ft AGL at 3nm, you have a damn good view (without twisting your neck off) of the whole airfield and any circuit traffic that is actually visible. If you see none, you can go straight in. If you see some in the (say LH) circuit, you can break off to the right and then turn left to do a crosswind join. On the CW join you have to fit yourself into any traffic currently downwind... but there is no way around having to fit in at some stage.
There is no perfect solution, but I absolutely do not accept that there is anything safe about the OHJ.
I especially don't like the OHJ because when things get really busy at an ATC airfield, the tower tends to revert to the OHJ when they can only just cope with what is happening lower down, and sending people to the overhead puts them where the tower doesn't have to worry about them. So, there you are, going round and round at 2000ft, with several others who you can't see and who can't see you. Not so clever. In such a situation I clear off and come back half an hour later...
Also, there is no "guarantee" of no traffic, unless it is an ATC airfield in which case you can assume there is some level of control.