The buying at 21 could also be short covering from those who hoped the deal would fall through. There's no way to tell, but this is one more possible scenario to add to the things you already mentioned. I'm not sure if I understand the rationale for holding VLSI now. A higher deal is unlikely and there's a lot of downside risk in the unlikely event that the deal falls through. It seems like one is just tying up money in a security with a lot of downside risk and little upside potential.
You mentioned GUMM. The stock has a solid base at 9 1/2 and I think a lot of good news is on the horizon. This is one my favorite buys right now from a risk/reward perspective.
Best of luck to all,