My understanding is that any shareholder can buy into the rights...

My understanding is that any shareholder can buy into the rights issue and also apply for any shortfall. SER (as a major shareholder) could participate to the extent of Chimarea's $6.3m. IMO SER participation in the RI is unlikely, due to unsecured creditors being offered 1c a share to pay off their debt. Also SER:

1. Do not have have Chimaeara's $6.3m and are unlikely to be selling out their 20% share in the Ionic IPO (whenever that happens).
2. It's doubtful that at this stage whether SER's 20% would raise $6.3m and certainly not the $6m for unsecured creditors
2. They are more likely to spend any money from Ionic (if they sell their 20% stake) on exploration of the mineral sands in WA (they are after all a mining/exploration company).
3. I am unsure that agreement currently in place with the unsecured creditors to accept payment in VXL shares (@1c each); they may refuse to accept payment in this manner.
4. SER (then Eagle Bay) carried Uley at $3,567,448 in 2003 accounts and even with the money spent plant and equipment in 2014/2015 is unlikely to be worth much more than $4m in a fire sale (it was carried at $8,554,085 (including $147,899 for motor vehicles which have probably been sold) in 2015 accounts).
5. After a RI and sale of shares to unsecured creditors there would he 2,629,016,214 shares on issue and 630,000,000, 1.5c options). Around ~20:1 consolidation would be necessary to bring this to a reasonable figure

I am not a lawyer but have in the past been involved in winding up a company. My understanding is that any of the creditors (secured and unsecured) can put a company into liquidation or the company themselves can go into voluntary liquidation. I don't know where VXL is going to get the money from for the RI (the 2014 RI & seed capital cost them $985,111 and the 2015 placement and SPP $872,431 - ref 2015 Annual report). If the RI does not get away or does not raise a significant part (i.e ~50%) of the secured debt then I suspect the creditors will put VXL into liquidation and any subscriptions to the RI lost.

Always be aware that once VXL is recapitalized $12m ($7m plant and $5m working capital) will need need to be raised, although I feel that with careful staging of the $7m plant capital it could be done for about $10m. A restructured VXL without secured and unsecured debt may be able to raise offtake finance for the $7m (particularly if they can get export credit guarantees).