Especially with the zerging system in place, I see no issue here. Hell, id just make the zergs far more intense for abuse in this manner. the best solution I could possibly give is making it cost an ap or two to give AND recieve an item. the refreshes happen every five minutes so doing it this way doesnt sound to bad. plus, itll equate to searching and finding on the first try, so if you try using an alt you wont save much ap even without the zerg punishment. if you also require the giving and recieving characters to be online, it CAN still be abused but it wouldnt be easy or convenient.
at any point, there are many different ways to abuse an alt and many of those ways are just impossible to stop. alt scouting is easily the best way to save ap, you could memorize the location of prey on the map ad infinatum with enough alts but we should hope that the player base isnt THAT desperate to cheat. by not banning alts, there are things that can abused from the get go in a game meant for a single player per character to engage in. but we allow alts, and while im fine with it the possibility of alt abuse is inevitable. if at any point a feature may incur alt abuse, it wont be because of the specific feature, but the existence of alts in general.
tldr if you make recieving an item cost an ap and force both players to be online in order to make the trade, you should be fine