Strictly speaking, the resident has changed the Common Property (antenna) without first obtaining the written consent of the Owners Corporation (O/C), and they could be required to restore it to its original (presumably non-operating) state, whereupon the O/C would be required to have it replaced again .
All quite silly really – like how much money are we talking about?
It sounds like the O/C only paid for the roof tile repairs, in which case I’d be inclined let sleeping dogs lie.
However as the O/C is held responsible to maintain and repair whatever style / quality of antenna and cabling the resident has installed, your Executive Committee Secretary should instruct the Strata Manager to advise that resident in writing that they’re not to make any further additions or changes to the Common Property, and that whilst for safety reasons any future maintenance and repairs to the newly installed antenna must be arranged by the O/C, that will be at cost to the resident (as its their antenna).