Looking on the positive side, your friend now has evidence that that EC member is willfully breaking the by-laws and fully intends to do so in the future.
I suggest putting forward two motions for the next EC meeting. The first is a motion to issue a Notice To Comply to the EC member concerned, telling them to stop parking in visitors parking. Don't brook any nonsense about issuing a warning first – a Notice To Comply is a warning, albeit one that carries a sting in its tail if it's ignored. Failure to do so will be a signal to all residents that visitor's parking ins now available to all and sundry.
Secondly, there should be a motion of censure on the EC member for using intimidating language and bullying tactics against an owner. Again you have the letter as evidence. It's very important in any civilised community that everyone band together to protect individuals from these jumped up power freaks who think membership of the EC is more about privilege than responsibility.
It would help greatly if the motions were accompanied by a letter signed by other residents asking the EC member to apologise publicly to the aggrieved owner. It's important that she doesn't feel she's alone.
Finally, this expensive equipment that he speaks of obviously isn't important enough for him to either hire a car space or make the effort of locking it in his garage. The truth is he's lazy and has a sense of entitlement … behaving like a member of the aristocracy or a spoiled teenage brat. This is something, no doubt, that will be recalled the next time he's up for election.
By the way, there is no legal compulsion on ECs to enforce by-laws … but your friend can go to Fair Trading and ask for a mediation followed by a Notice To Comply issued by them. But again, she – and more importantly, he – needs to know that she has the non EC members of the community behind her.