Trend Micro Titanium 2011 won't install with MalwareBytes on the machine

[VirtualLarry]

It had an older version of TM on the machine that did an update, which failed, which prompted me, which had a web KB article, which instructed me to download and install TM Titanium 2011. Which then prompted me to uninstall TM (expected), but it also prompted me to uninstall MalwareBytes (unexpected). I run MWB as an on-demand scanner only, not with the realtime scanner.

Is this just extreme product competition? Why is TM removing competitors products from the computer?