Yeah, while that sucks I would say that it's not really something I would blame them for. Not sure what it'd require in terms of infrastructure/setting things up on their backend to incorporate lightning deposits/withdrawals for every user. Would be cool to see.
Kind of strange that they are doing such hardcore chainalysis on deposits like this, especially such small amounts.
Wonder what their standards/settings are for determining what makes a transaction flagged as suspicious or being "linked" to "dirty bitcoins"...when you consider just how many millions of BTC flowed through sites like Silk Road back in the day, a huge number of BTC could theoretically be tied to "dirty coins", no?