Well I suspect St Kilda have a right to suspend him if he has been charged or convicted etc but at the moment (and not saying that won't change), he has not been charged let alone convicted.
I suspect Lovett has a case here as you can't just suspend someone without charges or even doing anything wrong that they can prove.
I wouldn't be surprised if the Saints are made to take him back. Lovett is just going through the process. Lets not forget under the Capuano rulings you can't sack a player midseason so if charges aren't laid or he is not convicted the Saints will have Andrew Lovett playing with them. The AFL rules on this are very specific.
I don't think forcing him back to St Kilda is the right answer for anyone. If they don't want him anymore, they should simply be forced to release him, allowing him to play in another league and an agreement on payment should be reached between the two parties (or by AFL mediation if required). If or when he is charged, the AFL can deal with the situation.
The nitty gritty of his place on the list and salary cap issues for the Saints would also need to be assessed. The only way I can see for them to get any leniency on these is for him to be charged with an offence significant enough for him to be deregistered by the AFL, but I'm not certain this would even change anything?