Trolling is the act of deliberately causing disruption for personal enjoyment.
In my view spamming can be considered part of trolling, if the intent was to elicit "lulzy" response from someone. I mean, who in their right mind would send such a private message to anyone unless they were expecting something to laugh about?
So yes, the accusation of trolling in this case is definitely not an unfounded one.
This not-so-expert legal quack opinion will cost you $500, which I would like to have in used banknotes.